1 /*
   2  * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "libadt/vectset.hpp"
  29 #include "memory/allocation.inline.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "opto/ad.hpp"
  32 #include "opto/callGenerator.hpp"
  33 #include "opto/castnode.hpp"
  34 #include "opto/cfgnode.hpp"
  35 #include "opto/connode.hpp"

  36 #include "opto/loopnode.hpp"
  37 #include "opto/machnode.hpp"
  38 #include "opto/matcher.hpp"
  39 #include "opto/node.hpp"
  40 #include "opto/opcodes.hpp"
  41 #include "opto/regmask.hpp"
  42 #include "opto/rootnode.hpp"
  43 #include "opto/type.hpp"
  44 #include "utilities/copy.hpp"
  45 #include "utilities/macros.hpp"
  46 #include "utilities/powerOfTwo.hpp"
  47 #include "utilities/stringUtils.hpp"
  48 
  49 class RegMask;
  50 // #include "phase.hpp"
  51 class PhaseTransform;
  52 class PhaseGVN;
  53 
  54 // Arena we are currently building Nodes in
  55 const uint Node::NotAMachineReg = 0xffff0000;
  56 
  57 #ifndef PRODUCT
  58 extern uint nodes_created;
  59 #endif
  60 #ifdef __clang__
  61 #pragma clang diagnostic push
  62 #pragma GCC diagnostic ignored "-Wuninitialized"
  63 #endif
  64 
  65 #ifdef ASSERT
  66 
  67 //-------------------------- construct_node------------------------------------
  68 // Set a breakpoint here to identify where a particular node index is built.
  69 void Node::verify_construction() {
  70   _debug_orig = nullptr;
  71   // The decimal digits of _debug_idx are <compile_id> followed by 10 digits of <_idx>
  72   Compile* C = Compile::current();
  73   assert(C->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  74   uint64_t new_debug_idx = (uint64_t)C->compile_id() * 10000000000 + _idx;
  75   set_debug_idx(new_debug_idx);
  76   if (!C->phase_optimize_finished()) {
  77     // Only check assert during parsing and optimization phase. Skip it while generating code.
  78     assert(C->live_nodes() <= C->max_node_limit(), "Live Node limit exceeded limit");
  79   }
  80   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (uint64_t)_idx == BreakAtNode)) {
  81     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT, _idx, _debug_idx);
  82     BREAKPOINT;
  83   }
  84 #if OPTO_DU_ITERATOR_ASSERT
  85   _last_del = nullptr;
  86   _del_tick = 0;
  87 #endif
  88   _hash_lock = 0;
  89 }
  90 
  91 
  92 // #ifdef ASSERT ...
  93 
  94 #if OPTO_DU_ITERATOR_ASSERT
  95 void DUIterator_Common::sample(const Node* node) {
  96   _vdui     = VerifyDUIterators;
  97   _node     = node;
  98   _outcnt   = node->_outcnt;
  99   _del_tick = node->_del_tick;
 100   _last     = nullptr;
 101 }
 102 
 103 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 104   assert(_node     == node, "consistent iterator source");
 105   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 106 }
 107 
 108 void DUIterator_Common::verify_resync() {
 109   // Ensure that the loop body has just deleted the last guy produced.
 110   const Node* node = _node;
 111   // Ensure that at least one copy of the last-seen edge was deleted.
 112   // Note:  It is OK to delete multiple copies of the last-seen edge.
 113   // Unfortunately, we have no way to verify that all the deletions delete
 114   // that same edge.  On this point we must use the Honor System.
 115   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 116   assert(node->_last_del == _last, "must have deleted the edge just produced");
 117   // We liked this deletion, so accept the resulting outcnt and tick.
 118   _outcnt   = node->_outcnt;
 119   _del_tick = node->_del_tick;
 120 }
 121 
 122 void DUIterator_Common::reset(const DUIterator_Common& that) {
 123   if (this == &that)  return;  // ignore assignment to self
 124   if (!_vdui) {
 125     // We need to initialize everything, overwriting garbage values.
 126     _last = that._last;
 127     _vdui = that._vdui;
 128   }
 129   // Note:  It is legal (though odd) for an iterator over some node x
 130   // to be reassigned to iterate over another node y.  Some doubly-nested
 131   // progress loops depend on being able to do this.
 132   const Node* node = that._node;
 133   // Re-initialize everything, except _last.
 134   _node     = node;
 135   _outcnt   = node->_outcnt;
 136   _del_tick = node->_del_tick;
 137 }
 138 
 139 void DUIterator::sample(const Node* node) {
 140   DUIterator_Common::sample(node);      // Initialize the assertion data.
 141   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 142 }
 143 
 144 void DUIterator::verify(const Node* node, bool at_end_ok) {
 145   DUIterator_Common::verify(node, at_end_ok);
 146   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 147 }
 148 
 149 void DUIterator::verify_increment() {
 150   if (_refresh_tick & 1) {
 151     // We have refreshed the index during this loop.
 152     // Fix up _idx to meet asserts.
 153     if (_idx > _outcnt)  _idx = _outcnt;
 154   }
 155   verify(_node, true);
 156 }
 157 
 158 void DUIterator::verify_resync() {
 159   // Note:  We do not assert on _outcnt, because insertions are OK here.
 160   DUIterator_Common::verify_resync();
 161   // Make sure we are still in sync, possibly with no more out-edges:
 162   verify(_node, true);
 163 }
 164 
 165 void DUIterator::reset(const DUIterator& that) {
 166   if (this == &that)  return;  // self assignment is always a no-op
 167   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 168   assert(that._idx          == 0, "assign only the result of Node::outs()");
 169   assert(_idx               == that._idx, "already assigned _idx");
 170   if (!_vdui) {
 171     // We need to initialize everything, overwriting garbage values.
 172     sample(that._node);
 173   } else {
 174     DUIterator_Common::reset(that);
 175     if (_refresh_tick & 1) {
 176       _refresh_tick++;                  // Clear the "was refreshed" flag.
 177     }
 178     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 179   }
 180 }
 181 
 182 void DUIterator::refresh() {
 183   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 184   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 185 }
 186 
 187 void DUIterator::verify_finish() {
 188   // If the loop has killed the node, do not require it to re-run.
 189   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 190   // If this assert triggers, it means that a loop used refresh_out_pos
 191   // to re-synch an iteration index, but the loop did not correctly
 192   // re-run itself, using a "while (progress)" construct.
 193   // This iterator enforces the rule that you must keep trying the loop
 194   // until it "runs clean" without any need for refreshing.
 195   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 196 }
 197 
 198 
 199 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 200   DUIterator_Common::verify(node, at_end_ok);
 201   Node** out    = node->_out;
 202   uint   cnt    = node->_outcnt;
 203   assert(cnt == _outcnt, "no insertions allowed");
 204   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 205   // This last check is carefully designed to work for NO_OUT_ARRAY.
 206 }
 207 
 208 void DUIterator_Fast::verify_limit() {
 209   const Node* node = _node;
 210   verify(node, true);
 211   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 212 }
 213 
 214 void DUIterator_Fast::verify_resync() {
 215   const Node* node = _node;
 216   if (_outp == node->_out + _outcnt) {
 217     // Note that the limit imax, not the pointer i, gets updated with the
 218     // exact count of deletions.  (For the pointer it's always "--i".)
 219     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 220     // This is a limit pointer, with a name like "imax".
 221     // Fudge the _last field so that the common assert will be happy.
 222     _last = (Node*) node->_last_del;
 223     DUIterator_Common::verify_resync();
 224   } else {
 225     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 226     // A normal internal pointer.
 227     DUIterator_Common::verify_resync();
 228     // Make sure we are still in sync, possibly with no more out-edges:
 229     verify(node, true);
 230   }
 231 }
 232 
 233 void DUIterator_Fast::verify_relimit(uint n) {
 234   const Node* node = _node;
 235   assert((int)n > 0, "use imax -= n only with a positive count");
 236   // This must be a limit pointer, with a name like "imax".
 237   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 238   // The reported number of deletions must match what the node saw.
 239   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 240   // Fudge the _last field so that the common assert will be happy.
 241   _last = (Node*) node->_last_del;
 242   DUIterator_Common::verify_resync();
 243 }
 244 
 245 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 246   assert(_outp              == that._outp, "already assigned _outp");
 247   DUIterator_Common::reset(that);
 248 }
 249 
 250 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 251   // at_end_ok means the _outp is allowed to underflow by 1
 252   _outp += at_end_ok;
 253   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 254   _outp -= at_end_ok;
 255   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 256 }
 257 
 258 void DUIterator_Last::verify_limit() {
 259   // Do not require the limit address to be resynched.
 260   //verify(node, true);
 261   assert(_outp == _node->_out, "limit still correct");
 262 }
 263 
 264 void DUIterator_Last::verify_step(uint num_edges) {
 265   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 266   _outcnt   -= num_edges;
 267   _del_tick += num_edges;
 268   // Make sure we are still in sync, possibly with no more out-edges:
 269   const Node* node = _node;
 270   verify(node, true);
 271   assert(node->_last_del == _last, "must have deleted the edge just produced");
 272 }
 273 
 274 #endif //OPTO_DU_ITERATOR_ASSERT
 275 
 276 
 277 #endif //ASSERT
 278 
 279 
 280 // This constant used to initialize _out may be any non-null value.
 281 // The value null is reserved for the top node only.
 282 #define NO_OUT_ARRAY ((Node**)-1)
 283 
 284 // Out-of-line code from node constructors.
 285 // Executed only when extra debug info. is being passed around.
 286 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 287   C->set_node_notes_at(idx, nn);
 288 }
 289 
 290 // Shared initialization code.
 291 inline int Node::Init(int req) {
 292   Compile* C = Compile::current();
 293   int idx = C->next_unique();
 294   NOT_PRODUCT(_igv_idx = C->next_igv_idx());
 295 
 296   // Allocate memory for the necessary number of edges.
 297   if (req > 0) {
 298     // Allocate space for _in array to have double alignment.
 299     _in = (Node **) ((char *) (C->node_arena()->AmallocWords(req * sizeof(void*))));
 300   }
 301   // If there are default notes floating around, capture them:
 302   Node_Notes* nn = C->default_node_notes();
 303   if (nn != nullptr)  init_node_notes(C, idx, nn);
 304 
 305   // Note:  At this point, C is dead,
 306   // and we begin to initialize the new Node.
 307 
 308   _cnt = _max = req;
 309   _outcnt = _outmax = 0;
 310   _class_id = Class_Node;
 311   _flags = 0;
 312   _out = NO_OUT_ARRAY;
 313   return idx;
 314 }
 315 
 316 //------------------------------Node-------------------------------------------
 317 // Create a Node, with a given number of required edges.
 318 Node::Node(uint req)
 319   : _idx(Init(req))
 320 #ifdef ASSERT
 321   , _parse_idx(_idx)
 322 #endif
 323 {
 324   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 325   debug_only( verify_construction() );
 326   NOT_PRODUCT(nodes_created++);
 327   if (req == 0) {
 328     _in = nullptr;
 329   } else {
 330     Node** to = _in;
 331     for(uint i = 0; i < req; i++) {
 332       to[i] = nullptr;
 333     }
 334   }
 335 }
 336 
 337 //------------------------------Node-------------------------------------------
 338 Node::Node(Node *n0)
 339   : _idx(Init(1))
 340 #ifdef ASSERT
 341   , _parse_idx(_idx)
 342 #endif
 343 {
 344   debug_only( verify_construction() );
 345   NOT_PRODUCT(nodes_created++);
 346   assert( is_not_dead(n0), "can not use dead node");
 347   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 348 }
 349 
 350 //------------------------------Node-------------------------------------------
 351 Node::Node(Node *n0, Node *n1)
 352   : _idx(Init(2))
 353 #ifdef ASSERT
 354   , _parse_idx(_idx)
 355 #endif
 356 {
 357   debug_only( verify_construction() );
 358   NOT_PRODUCT(nodes_created++);
 359   assert( is_not_dead(n0), "can not use dead node");
 360   assert( is_not_dead(n1), "can not use dead node");
 361   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 362   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 363 }
 364 
 365 //------------------------------Node-------------------------------------------
 366 Node::Node(Node *n0, Node *n1, Node *n2)
 367   : _idx(Init(3))
 368 #ifdef ASSERT
 369   , _parse_idx(_idx)
 370 #endif
 371 {
 372   debug_only( verify_construction() );
 373   NOT_PRODUCT(nodes_created++);
 374   assert( is_not_dead(n0), "can not use dead node");
 375   assert( is_not_dead(n1), "can not use dead node");
 376   assert( is_not_dead(n2), "can not use dead node");
 377   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 378   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 379   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 380 }
 381 
 382 //------------------------------Node-------------------------------------------
 383 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 384   : _idx(Init(4))
 385 #ifdef ASSERT
 386   , _parse_idx(_idx)
 387 #endif
 388 {
 389   debug_only( verify_construction() );
 390   NOT_PRODUCT(nodes_created++);
 391   assert( is_not_dead(n0), "can not use dead node");
 392   assert( is_not_dead(n1), "can not use dead node");
 393   assert( is_not_dead(n2), "can not use dead node");
 394   assert( is_not_dead(n3), "can not use dead node");
 395   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 396   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 397   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 398   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 399 }
 400 
 401 //------------------------------Node-------------------------------------------
 402 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 403   : _idx(Init(5))
 404 #ifdef ASSERT
 405   , _parse_idx(_idx)
 406 #endif
 407 {
 408   debug_only( verify_construction() );
 409   NOT_PRODUCT(nodes_created++);
 410   assert( is_not_dead(n0), "can not use dead node");
 411   assert( is_not_dead(n1), "can not use dead node");
 412   assert( is_not_dead(n2), "can not use dead node");
 413   assert( is_not_dead(n3), "can not use dead node");
 414   assert( is_not_dead(n4), "can not use dead node");
 415   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 416   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 417   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 418   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 419   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 420 }
 421 
 422 //------------------------------Node-------------------------------------------
 423 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 424                      Node *n4, Node *n5)
 425   : _idx(Init(6))
 426 #ifdef ASSERT
 427   , _parse_idx(_idx)
 428 #endif
 429 {
 430   debug_only( verify_construction() );
 431   NOT_PRODUCT(nodes_created++);
 432   assert( is_not_dead(n0), "can not use dead node");
 433   assert( is_not_dead(n1), "can not use dead node");
 434   assert( is_not_dead(n2), "can not use dead node");
 435   assert( is_not_dead(n3), "can not use dead node");
 436   assert( is_not_dead(n4), "can not use dead node");
 437   assert( is_not_dead(n5), "can not use dead node");
 438   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 439   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 440   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 441   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 442   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 443   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 444 }
 445 
 446 //------------------------------Node-------------------------------------------
 447 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 448                      Node *n4, Node *n5, Node *n6)
 449   : _idx(Init(7))
 450 #ifdef ASSERT
 451   , _parse_idx(_idx)
 452 #endif
 453 {
 454   debug_only( verify_construction() );
 455   NOT_PRODUCT(nodes_created++);
 456   assert( is_not_dead(n0), "can not use dead node");
 457   assert( is_not_dead(n1), "can not use dead node");
 458   assert( is_not_dead(n2), "can not use dead node");
 459   assert( is_not_dead(n3), "can not use dead node");
 460   assert( is_not_dead(n4), "can not use dead node");
 461   assert( is_not_dead(n5), "can not use dead node");
 462   assert( is_not_dead(n6), "can not use dead node");
 463   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 464   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 465   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 466   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 467   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 468   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 469   _in[6] = n6; if (n6 != nullptr) n6->add_out((Node *)this);
 470 }
 471 
 472 #ifdef __clang__
 473 #pragma clang diagnostic pop
 474 #endif
 475 
 476 
 477 //------------------------------clone------------------------------------------
 478 // Clone a Node.
 479 Node *Node::clone() const {
 480   Compile* C = Compile::current();
 481   uint s = size_of();           // Size of inherited Node
 482   Node *n = (Node*)C->node_arena()->AmallocWords(size_of() + _max*sizeof(Node*));
 483   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 484   // Set the new input pointer array
 485   n->_in = (Node**)(((char*)n)+s);
 486   // Cannot share the old output pointer array, so kill it
 487   n->_out = NO_OUT_ARRAY;
 488   // And reset the counters to 0
 489   n->_outcnt = 0;
 490   n->_outmax = 0;
 491   // Unlock this guy, since he is not in any hash table.
 492   debug_only(n->_hash_lock = 0);
 493   // Walk the old node's input list to duplicate its edges
 494   uint i;
 495   for( i = 0; i < len(); i++ ) {
 496     Node *x = in(i);
 497     n->_in[i] = x;
 498     if (x != nullptr) x->add_out(n);
 499   }
 500   if (is_macro()) {
 501     C->add_macro_node(n);
 502   }
 503   if (is_expensive()) {
 504     C->add_expensive_node(n);
 505   }
 506   if (for_post_loop_opts_igvn()) {
 507     // Don't add cloned node to Compile::_for_post_loop_opts_igvn list automatically.
 508     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 509     n->remove_flag(Node::NodeFlags::Flag_for_post_loop_opts_igvn);
 510   }
 511   if (n->is_ParsePredicate()) {
 512     C->add_parse_predicate(n->as_ParsePredicate());
 513   }
 514 
 515   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 516   bs->register_potential_barrier_node(n);
 517 
 518   n->set_idx(C->next_unique()); // Get new unique index as well
 519   NOT_PRODUCT(n->_igv_idx = C->next_igv_idx());
 520   debug_only( n->verify_construction() );
 521   NOT_PRODUCT(nodes_created++);
 522   // Do not patch over the debug_idx of a clone, because it makes it
 523   // impossible to break on the clone's moment of creation.
 524   //debug_only( n->set_debug_idx( debug_idx() ) );
 525 
 526   C->copy_node_notes_to(n, (Node*) this);
 527 
 528   // MachNode clone
 529   uint nopnds;
 530   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 531     MachNode *mach  = n->as_Mach();
 532     MachNode *mthis = this->as_Mach();
 533     // Get address of _opnd_array.
 534     // It should be the same offset since it is the clone of this node.
 535     MachOper **from = mthis->_opnds;
 536     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 537                     pointer_delta((const void*)from,
 538                                   (const void*)(&mthis->_opnds), 1));
 539     mach->_opnds = to;
 540     for ( uint i = 0; i < nopnds; ++i ) {
 541       to[i] = from[i]->clone();
 542     }
 543   }
 544   if (n->is_Call()) {
 545     // CallGenerator is linked to the original node.
 546     CallGenerator* cg = n->as_Call()->generator();
 547     if (cg != nullptr) {
 548       CallGenerator* cloned_cg = cg->with_call_node(n->as_Call());
 549       n->as_Call()->set_generator(cloned_cg);
 550 
 551       C->print_inlining_assert_ready();
 552       C->print_inlining_move_to(cg);
 553       C->print_inlining_update(cloned_cg);
 554     }
 555   }
 556   if (n->is_SafePoint()) {
 557     // Scalar replacement and macro expansion might modify the JVMState.
 558     // Clone it to make sure it's not shared between SafePointNodes.
 559     n->as_SafePoint()->clone_jvms(C);
 560     n->as_SafePoint()->clone_replaced_nodes();
 561   }



 562   Compile::current()->record_modified_node(n);
 563   return n;                     // Return the clone
 564 }
 565 
 566 //---------------------------setup_is_top--------------------------------------
 567 // Call this when changing the top node, to reassert the invariants
 568 // required by Node::is_top.  See Compile::set_cached_top_node.
 569 void Node::setup_is_top() {
 570   if (this == (Node*)Compile::current()->top()) {
 571     // This node has just become top.  Kill its out array.
 572     _outcnt = _outmax = 0;
 573     _out = nullptr;                           // marker value for top
 574     assert(is_top(), "must be top");
 575   } else {
 576     if (_out == nullptr)  _out = NO_OUT_ARRAY;
 577     assert(!is_top(), "must not be top");
 578   }
 579 }
 580 
 581 //------------------------------~Node------------------------------------------
 582 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 583 void Node::destruct(PhaseValues* phase) {
 584   Compile* compile = (phase != nullptr) ? phase->C : Compile::current();
 585   if (phase != nullptr && phase->is_IterGVN()) {
 586     phase->is_IterGVN()->_worklist.remove(this);
 587   }
 588   // If this is the most recently created node, reclaim its index. Otherwise,
 589   // record the node as dead to keep liveness information accurate.
 590   if ((uint)_idx+1 == compile->unique()) {
 591     compile->set_unique(compile->unique()-1);
 592   } else {
 593     compile->record_dead_node(_idx);
 594   }
 595   // Clear debug info:
 596   Node_Notes* nn = compile->node_notes_at(_idx);
 597   if (nn != nullptr)  nn->clear();
 598   // Walk the input array, freeing the corresponding output edges
 599   _cnt = _max;  // forget req/prec distinction
 600   uint i;
 601   for( i = 0; i < _max; i++ ) {
 602     set_req(i, nullptr);
 603     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 604   }
 605   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 606 
 607   if (is_macro()) {
 608     compile->remove_macro_node(this);
 609   }
 610   if (is_expensive()) {
 611     compile->remove_expensive_node(this);
 612   }
 613   if (Opcode() == Op_Opaque4) {
 614     compile->remove_template_assertion_predicate_opaq(this);
 615   }
 616   if (is_ParsePredicate()) {
 617     compile->remove_parse_predicate(as_ParsePredicate());
 618   }
 619   if (for_post_loop_opts_igvn()) {
 620     compile->remove_from_post_loop_opts_igvn(this);
 621   }



 622 
 623   if (is_SafePoint()) {
 624     as_SafePoint()->delete_replaced_nodes();
 625 
 626     if (is_CallStaticJava()) {
 627       compile->remove_unstable_if_trap(as_CallStaticJava(), false);
 628     }
 629   }
 630   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 631   bs->unregister_potential_barrier_node(this);
 632 
 633   // See if the input array was allocated just prior to the object
 634   int edge_size = _max*sizeof(void*);
 635   int out_edge_size = _outmax*sizeof(void*);
 636   char *in_array = ((char*)_in);
 637   char *edge_end = in_array + edge_size;
 638   char *out_array = (char*)(_out == NO_OUT_ARRAY? nullptr: _out);
 639   int node_size = size_of();
 640 
 641 #ifdef ASSERT
 642   // We will not actually delete the storage, but we'll make the node unusable.
 643   compile->remove_modified_node(this);
 644   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 645   _in = _out = (Node**) badAddress;
 646   _max = _cnt = _outmax = _outcnt = 0;
 647 #endif
 648 
 649   // Free the output edge array
 650   if (out_edge_size > 0) {
 651     compile->node_arena()->Afree(out_array, out_edge_size);
 652   }
 653 
 654   // Free the input edge array and the node itself
 655   if( edge_end == (char*)this ) {
 656     // It was; free the input array and object all in one hit
 657 #ifndef ASSERT
 658     compile->node_arena()->Afree(in_array, edge_size+node_size);
 659 #endif
 660   } else {
 661     // Free just the input array
 662     compile->node_arena()->Afree(in_array, edge_size);
 663 
 664     // Free just the object
 665 #ifndef ASSERT
 666     compile->node_arena()->Afree(this, node_size);
 667 #endif
 668   }
 669 }
 670 
 671 //------------------------------grow-------------------------------------------
 672 // Grow the input array, making space for more edges
 673 void Node::grow(uint len) {
 674   Arena* arena = Compile::current()->node_arena();
 675   uint new_max = _max;
 676   if( new_max == 0 ) {
 677     _max = 4;
 678     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 679     Node** to = _in;
 680     to[0] = nullptr;
 681     to[1] = nullptr;
 682     to[2] = nullptr;
 683     to[3] = nullptr;
 684     return;
 685   }
 686   new_max = next_power_of_2(len);
 687   // Trimming to limit allows a uint8 to handle up to 255 edges.
 688   // Previously I was using only powers-of-2 which peaked at 128 edges.
 689   //if( new_max >= limit ) new_max = limit-1;
 690   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 691   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // null all new space
 692   _max = new_max;               // Record new max length
 693   // This assertion makes sure that Node::_max is wide enough to
 694   // represent the numerical value of new_max.
 695   assert(_max == new_max && _max > len, "int width of _max is too small");
 696 }
 697 
 698 //-----------------------------out_grow----------------------------------------
 699 // Grow the input array, making space for more edges
 700 void Node::out_grow( uint len ) {
 701   assert(!is_top(), "cannot grow a top node's out array");
 702   Arena* arena = Compile::current()->node_arena();
 703   uint new_max = _outmax;
 704   if( new_max == 0 ) {
 705     _outmax = 4;
 706     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 707     return;
 708   }
 709   new_max = next_power_of_2(len);
 710   // Trimming to limit allows a uint8 to handle up to 255 edges.
 711   // Previously I was using only powers-of-2 which peaked at 128 edges.
 712   //if( new_max >= limit ) new_max = limit-1;
 713   assert(_out != nullptr && _out != NO_OUT_ARRAY, "out must have sensible value");
 714   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 715   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // null all new space
 716   _outmax = new_max;               // Record new max length
 717   // This assertion makes sure that Node::_max is wide enough to
 718   // represent the numerical value of new_max.
 719   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 720 }
 721 
 722 #ifdef ASSERT
 723 //------------------------------is_dead----------------------------------------
 724 bool Node::is_dead() const {
 725   // Mach and pinch point nodes may look like dead.
 726   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 727     return false;
 728   for( uint i = 0; i < _max; i++ )
 729     if( _in[i] != nullptr )
 730       return false;
 731   return true;
 732 }
 733 
 734 bool Node::is_not_dead(const Node* n) {
 735   return n == nullptr || !PhaseIterGVN::is_verify_def_use() || !(n->is_dead());
 736 }
 737 
 738 bool Node::is_reachable_from_root() const {
 739   ResourceMark rm;
 740   Unique_Node_List wq;
 741   wq.push((Node*)this);
 742   RootNode* root = Compile::current()->root();
 743   for (uint i = 0; i < wq.size(); i++) {
 744     Node* m = wq.at(i);
 745     if (m == root) {
 746       return true;
 747     }
 748     for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
 749       Node* u = m->fast_out(j);
 750       wq.push(u);
 751     }
 752   }
 753   return false;
 754 }
 755 #endif
 756 
 757 //------------------------------is_unreachable---------------------------------
 758 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 759   assert(!is_Mach(), "doesn't work with MachNodes");
 760   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != nullptr && in(0)->is_top());
 761 }
 762 
 763 //------------------------------add_req----------------------------------------
 764 // Add a new required input at the end
 765 void Node::add_req( Node *n ) {
 766   assert( is_not_dead(n), "can not use dead node");
 767 
 768   // Look to see if I can move precedence down one without reallocating
 769   if( (_cnt >= _max) || (in(_max-1) != nullptr) )
 770     grow( _max+1 );
 771 
 772   // Find a precedence edge to move
 773   if( in(_cnt) != nullptr ) {   // Next precedence edge is busy?
 774     uint i;
 775     for( i=_cnt; i<_max; i++ )
 776       if( in(i) == nullptr )    // Find the null at end of prec edge list
 777         break;                  // There must be one, since we grew the array
 778     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 779   }
 780   _in[_cnt++] = n;            // Stuff over old prec edge
 781   if (n != nullptr) n->add_out((Node *)this);
 782   Compile::current()->record_modified_node(this);
 783 }
 784 
 785 //---------------------------add_req_batch-------------------------------------
 786 // Add a new required input at the end
 787 void Node::add_req_batch( Node *n, uint m ) {
 788   assert( is_not_dead(n), "can not use dead node");
 789   // check various edge cases
 790   if ((int)m <= 1) {
 791     assert((int)m >= 0, "oob");
 792     if (m != 0)  add_req(n);
 793     return;
 794   }
 795 
 796   // Look to see if I can move precedence down one without reallocating
 797   if( (_cnt+m) > _max || _in[_max-m] )
 798     grow( _max+m );
 799 
 800   // Find a precedence edge to move
 801   if( _in[_cnt] != nullptr ) {  // Next precedence edge is busy?
 802     uint i;
 803     for( i=_cnt; i<_max; i++ )
 804       if( _in[i] == nullptr )   // Find the null at end of prec edge list
 805         break;                  // There must be one, since we grew the array
 806     // Slide all the precs over by m positions (assume #prec << m).
 807     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 808   }
 809 
 810   // Stuff over the old prec edges
 811   for(uint i=0; i<m; i++ ) {
 812     _in[_cnt++] = n;
 813   }
 814 
 815   // Insert multiple out edges on the node.
 816   if (n != nullptr && !n->is_top()) {
 817     for(uint i=0; i<m; i++ ) {
 818       n->add_out((Node *)this);
 819     }
 820   }
 821   Compile::current()->record_modified_node(this);
 822 }
 823 
 824 //------------------------------del_req----------------------------------------
 825 // Delete the required edge and compact the edge array
 826 void Node::del_req( uint idx ) {
 827   assert( idx < _cnt, "oob");
 828   assert( !VerifyHashTableKeys || _hash_lock == 0,
 829           "remove node from hash table before modifying it");
 830   // First remove corresponding def-use edge
 831   Node *n = in(idx);
 832   if (n != nullptr) n->del_out((Node *)this);
 833   _in[idx] = in(--_cnt); // Compact the array
 834   // Avoid spec violation: Gap in prec edges.
 835   close_prec_gap_at(_cnt);
 836   Compile::current()->record_modified_node(this);
 837 }
 838 
 839 //------------------------------del_req_ordered--------------------------------
 840 // Delete the required edge and compact the edge array with preserved order
 841 void Node::del_req_ordered( uint idx ) {
 842   assert( idx < _cnt, "oob");
 843   assert( !VerifyHashTableKeys || _hash_lock == 0,
 844           "remove node from hash table before modifying it");
 845   // First remove corresponding def-use edge
 846   Node *n = in(idx);
 847   if (n != nullptr) n->del_out((Node *)this);
 848   if (idx < --_cnt) {    // Not last edge ?
 849     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 850   }
 851   // Avoid spec violation: Gap in prec edges.
 852   close_prec_gap_at(_cnt);
 853   Compile::current()->record_modified_node(this);
 854 }
 855 
 856 //------------------------------ins_req----------------------------------------
 857 // Insert a new required input at the end
 858 void Node::ins_req( uint idx, Node *n ) {
 859   assert( is_not_dead(n), "can not use dead node");
 860   add_req(nullptr);                // Make space
 861   assert( idx < _max, "Must have allocated enough space");
 862   // Slide over
 863   if(_cnt-idx-1 > 0) {
 864     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 865   }
 866   _in[idx] = n;                            // Stuff over old required edge
 867   if (n != nullptr) n->add_out((Node *)this); // Add reciprocal def-use edge
 868   Compile::current()->record_modified_node(this);
 869 }
 870 
 871 //-----------------------------find_edge---------------------------------------
 872 int Node::find_edge(Node* n) {
 873   for (uint i = 0; i < len(); i++) {
 874     if (_in[i] == n)  return i;
 875   }
 876   return -1;
 877 }
 878 
 879 //----------------------------replace_edge-------------------------------------
 880 int Node::replace_edge(Node* old, Node* neww, PhaseGVN* gvn) {
 881   if (old == neww)  return 0;  // nothing to do
 882   uint nrep = 0;
 883   for (uint i = 0; i < len(); i++) {
 884     if (in(i) == old) {
 885       if (i < req()) {
 886         if (gvn != nullptr) {
 887           set_req_X(i, neww, gvn);
 888         } else {
 889           set_req(i, neww);
 890         }
 891       } else {
 892         assert(gvn == nullptr || gvn->is_IterGVN() == nullptr, "no support for igvn here");
 893         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 894         set_prec(i, neww);
 895       }
 896       nrep++;
 897     }
 898   }
 899   return nrep;
 900 }
 901 
 902 /**
 903  * Replace input edges in the range pointing to 'old' node.
 904  */
 905 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn) {
 906   if (old == neww)  return 0;  // nothing to do
 907   uint nrep = 0;
 908   for (int i = start; i < end; i++) {
 909     if (in(i) == old) {
 910       set_req_X(i, neww, gvn);
 911       nrep++;
 912     }
 913   }
 914   return nrep;
 915 }
 916 
 917 //-------------------------disconnect_inputs-----------------------------------
 918 // null out all inputs to eliminate incoming Def-Use edges.
 919 void Node::disconnect_inputs(Compile* C) {
 920   // the layout of Node::_in
 921   // r: a required input, null is allowed
 922   // p: a precedence, null values are all at the end
 923   // -----------------------------------
 924   // |r|...|r|p|...|p|null|...|null|
 925   //         |                     |
 926   //         req()                 len()
 927   // -----------------------------------
 928   for (uint i = 0; i < req(); ++i) {
 929     if (in(i) != nullptr) {
 930       set_req(i, nullptr);
 931     }
 932   }
 933 
 934   // Remove precedence edges if any exist
 935   // Note: Safepoints may have precedence edges, even during parsing
 936   for (uint i = len(); i > req(); ) {
 937     rm_prec(--i);  // no-op if _in[i] is null
 938   }
 939 
 940 #ifdef ASSERT
 941   // sanity check
 942   for (uint i = 0; i < len(); ++i) {
 943     assert(_in[i] == nullptr, "disconnect_inputs() failed!");
 944   }
 945 #endif
 946 
 947   // Node::destruct requires all out edges be deleted first
 948   // debug_only(destruct();)   // no reuse benefit expected
 949   C->record_dead_node(_idx);
 950 }
 951 
 952 //-----------------------------uncast---------------------------------------
 953 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 954 // Strip away casting.  (It is depth-limited.)
 955 // Optionally, keep casts with dependencies.
 956 Node* Node::uncast(bool keep_deps) const {
 957   // Should be inline:
 958   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 959   if (is_ConstraintCast()) {
 960     return uncast_helper(this, keep_deps);
 961   } else {
 962     return (Node*) this;
 963   }
 964 }
 965 
 966 // Find out of current node that matches opcode.
 967 Node* Node::find_out_with(int opcode) {
 968   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 969     Node* use = fast_out(i);
 970     if (use->Opcode() == opcode) {
 971       return use;
 972     }
 973   }
 974   return nullptr;
 975 }
 976 
 977 // Return true if the current node has an out that matches opcode.
 978 bool Node::has_out_with(int opcode) {
 979   return (find_out_with(opcode) != nullptr);
 980 }
 981 
 982 // Return true if the current node has an out that matches any of the opcodes.
 983 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 984   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 985       int opcode = fast_out(i)->Opcode();
 986       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 987         return true;
 988       }
 989   }
 990   return false;
 991 }
 992 
 993 
 994 //---------------------------uncast_helper-------------------------------------
 995 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
 996 #ifdef ASSERT
 997   uint depth_count = 0;
 998   const Node* orig_p = p;
 999 #endif
1000 
1001   while (true) {
1002 #ifdef ASSERT
1003     if (depth_count >= K) {
1004       orig_p->dump(4);
1005       if (p != orig_p)
1006         p->dump(1);
1007     }
1008     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
1009 #endif
1010     if (p == nullptr || p->req() != 2) {
1011       break;
1012     } else if (p->is_ConstraintCast()) {
1013       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
1014         break; // stop at casts with dependencies
1015       }
1016       p = p->in(1);
1017     } else {
1018       break;
1019     }
1020   }
1021   return (Node*) p;
1022 }
1023 
1024 //------------------------------add_prec---------------------------------------
1025 // Add a new precedence input.  Precedence inputs are unordered, with
1026 // duplicates removed and nulls packed down at the end.
1027 void Node::add_prec( Node *n ) {
1028   assert( is_not_dead(n), "can not use dead node");
1029 
1030   // Check for null at end
1031   if( _cnt >= _max || in(_max-1) )
1032     grow( _max+1 );
1033 
1034   // Find a precedence edge to move
1035   uint i = _cnt;
1036   while( in(i) != nullptr ) {
1037     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
1038     i++;
1039   }
1040   _in[i] = n;                                   // Stuff prec edge over null
1041   if ( n != nullptr) n->add_out((Node *)this);  // Add mirror edge
1042 
1043 #ifdef ASSERT
1044   while ((++i)<_max) { assert(_in[i] == nullptr, "spec violation: Gap in prec edges (node %d)", _idx); }
1045 #endif
1046   Compile::current()->record_modified_node(this);
1047 }
1048 
1049 //------------------------------rm_prec----------------------------------------
1050 // Remove a precedence input.  Precedence inputs are unordered, with
1051 // duplicates removed and nulls packed down at the end.
1052 void Node::rm_prec( uint j ) {
1053   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1054   assert(j >= _cnt, "not a precedence edge");
1055   if (_in[j] == nullptr) return;   // Avoid spec violation: Gap in prec edges.
1056   _in[j]->del_out((Node *)this);
1057   close_prec_gap_at(j);
1058   Compile::current()->record_modified_node(this);
1059 }
1060 
1061 //------------------------------size_of----------------------------------------
1062 uint Node::size_of() const { return sizeof(*this); }
1063 
1064 //------------------------------ideal_reg--------------------------------------
1065 uint Node::ideal_reg() const { return 0; }
1066 
1067 //------------------------------jvms-------------------------------------------
1068 JVMState* Node::jvms() const { return nullptr; }
1069 
1070 #ifdef ASSERT
1071 //------------------------------jvms-------------------------------------------
1072 bool Node::verify_jvms(const JVMState* using_jvms) const {
1073   for (JVMState* jvms = this->jvms(); jvms != nullptr; jvms = jvms->caller()) {
1074     if (jvms == using_jvms)  return true;
1075   }
1076   return false;
1077 }
1078 
1079 //------------------------------init_NodeProperty------------------------------
1080 void Node::init_NodeProperty() {
1081   assert(_max_classes <= max_juint, "too many NodeProperty classes");
1082   assert(max_flags() <= max_juint, "too many NodeProperty flags");
1083 }
1084 
1085 //-----------------------------max_flags---------------------------------------
1086 juint Node::max_flags() {
1087   return (PD::_last_flag << 1) - 1; // allow flags combination
1088 }
1089 #endif
1090 
1091 //------------------------------format-----------------------------------------
1092 // Print as assembly
1093 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1094 //------------------------------emit-------------------------------------------
1095 // Emit bytes starting at parameter 'ptr'.
1096 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1097 //------------------------------size-------------------------------------------
1098 // Size of instruction in bytes
1099 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1100 
1101 //------------------------------CFG Construction-------------------------------
1102 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1103 // Goto and Return.
1104 const Node *Node::is_block_proj() const { return 0; }
1105 
1106 // Minimum guaranteed type
1107 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1108 
1109 
1110 //------------------------------raise_bottom_type------------------------------
1111 // Get the worst-case Type output for this Node.
1112 void Node::raise_bottom_type(const Type* new_type) {
1113   if (is_Type()) {
1114     TypeNode *n = this->as_Type();
1115     if (VerifyAliases) {
1116       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1117     }
1118     n->set_type(new_type);
1119   } else if (is_Load()) {
1120     LoadNode *n = this->as_Load();
1121     if (VerifyAliases) {
1122       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1123     }
1124     n->set_type(new_type);
1125   }
1126 }
1127 
1128 //------------------------------Identity---------------------------------------
1129 // Return a node that the given node is equivalent to.
1130 Node* Node::Identity(PhaseGVN* phase) {
1131   return this;                  // Default to no identities
1132 }
1133 
1134 //------------------------------Value------------------------------------------
1135 // Compute a new Type for a node using the Type of the inputs.
1136 const Type* Node::Value(PhaseGVN* phase) const {
1137   return bottom_type();         // Default to worst-case Type
1138 }
1139 
1140 //------------------------------Ideal------------------------------------------
1141 //
1142 // 'Idealize' the graph rooted at this Node.
1143 //
1144 // In order to be efficient and flexible there are some subtle invariants
1145 // these Ideal calls need to hold.  Running with '-XX:VerifyIterativeGVN=1' checks
1146 // these invariants, although its too slow to have on by default.  If you are
1147 // hacking an Ideal call, be sure to test with '-XX:VerifyIterativeGVN=1'
1148 //
1149 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1150 // pointer.  If ANY change is made, it must return the root of the reshaped
1151 // graph - even if the root is the same Node.  Example: swapping the inputs
1152 // to an AddINode gives the same answer and same root, but you still have to
1153 // return the 'this' pointer instead of null.
1154 //
1155 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1156 // Identity call to return an old Node; basically if Identity can find
1157 // another Node have the Ideal call make no change and return null.
1158 // Example: AddINode::Ideal must check for add of zero; in this case it
1159 // returns null instead of doing any graph reshaping.
1160 //
1161 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1162 // sharing there may be other users of the old Nodes relying on their current
1163 // semantics.  Modifying them will break the other users.
1164 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1165 // "X+3" unchanged in case it is shared.
1166 //
1167 // If you modify the 'this' pointer's inputs, you should use
1168 // 'set_req'.  If you are making a new Node (either as the new root or
1169 // some new internal piece) you may use 'init_req' to set the initial
1170 // value.  You can make a new Node with either 'new' or 'clone'.  In
1171 // either case, def-use info is correctly maintained.
1172 //
1173 // Example: reshape "(X+3)+4" into "X+7":
1174 //    set_req(1, in(1)->in(1));
1175 //    set_req(2, phase->intcon(7));
1176 //    return this;
1177 // Example: reshape "X*4" into "X<<2"
1178 //    return new LShiftINode(in(1), phase->intcon(2));
1179 //
1180 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1181 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1182 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1183 //    return new AddINode(shift, in(1));
1184 //
1185 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1186 // These forms are faster than 'phase->transform(new ConNode())' and Do
1187 // The Right Thing with def-use info.
1188 //
1189 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1190 // graph uses the 'this' Node it must be the root.  If you want a Node with
1191 // the same Opcode as the 'this' pointer use 'clone'.
1192 //
1193 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1194   return nullptr;                  // Default to being Ideal already
1195 }
1196 
1197 // Some nodes have specific Ideal subgraph transformations only if they are
1198 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1199 // for the transformations to happen.
1200 bool Node::has_special_unique_user() const {
1201   assert(outcnt() == 1, "match only for unique out");
1202   Node* n = unique_out();
1203   int op  = Opcode();
1204   if (this->is_Store()) {
1205     // Condition for back-to-back stores folding.
1206     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1207   } else if (this->is_Load() || this->is_DecodeN() || this->is_Phi()) {
1208     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1209     return n->Opcode() == Op_MemBarAcquire;
1210   } else if (op == Op_AddL) {
1211     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1212     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1213   } else if (op == Op_SubI || op == Op_SubL) {
1214     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1215     return n->Opcode() == op && n->in(2) == this;
1216   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1217     // See IfProjNode::Identity()
1218     return true;
1219   } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
1220     // See IfNode::fold_compares
1221     return true;
1222   } else {
1223     return false;
1224   }
1225 };
1226 
1227 //--------------------------find_exact_control---------------------------------
1228 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1229 Node* Node::find_exact_control(Node* ctrl) {
1230   if (ctrl == nullptr && this->is_Region())
1231     ctrl = this->as_Region()->is_copy();
1232 
1233   if (ctrl != nullptr && ctrl->is_CatchProj()) {
1234     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1235       ctrl = ctrl->in(0);
1236     if (ctrl != nullptr && !ctrl->is_top())
1237       ctrl = ctrl->in(0);
1238   }
1239 
1240   if (ctrl != nullptr && ctrl->is_Proj())
1241     ctrl = ctrl->in(0);
1242 
1243   return ctrl;
1244 }
1245 
1246 //--------------------------dominates------------------------------------------
1247 // Helper function for MemNode::all_controls_dominate().
1248 // Check if 'this' control node dominates or equal to 'sub' control node.
1249 // We already know that if any path back to Root or Start reaches 'this',
1250 // then all paths so, so this is a simple search for one example,
1251 // not an exhaustive search for a counterexample.
1252 bool Node::dominates(Node* sub, Node_List &nlist) {
1253   assert(this->is_CFG(), "expecting control");
1254   assert(sub != nullptr && sub->is_CFG(), "expecting control");
1255 
1256   // detect dead cycle without regions
1257   int iterations_without_region_limit = DominatorSearchLimit;
1258 
1259   Node* orig_sub = sub;
1260   Node* dom      = this;
1261   bool  met_dom  = false;
1262   nlist.clear();
1263 
1264   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1265   // After seeing 'dom', continue up to Root or Start.
1266   // If we hit a region (backward split point), it may be a loop head.
1267   // Keep going through one of the region's inputs.  If we reach the
1268   // same region again, go through a different input.  Eventually we
1269   // will either exit through the loop head, or give up.
1270   // (If we get confused, break out and return a conservative 'false'.)
1271   while (sub != nullptr) {
1272     if (sub->is_top())  break; // Conservative answer for dead code.
1273     if (sub == dom) {
1274       if (nlist.size() == 0) {
1275         // No Region nodes except loops were visited before and the EntryControl
1276         // path was taken for loops: it did not walk in a cycle.
1277         return true;
1278       } else if (met_dom) {
1279         break;          // already met before: walk in a cycle
1280       } else {
1281         // Region nodes were visited. Continue walk up to Start or Root
1282         // to make sure that it did not walk in a cycle.
1283         met_dom = true; // first time meet
1284         iterations_without_region_limit = DominatorSearchLimit; // Reset
1285      }
1286     }
1287     if (sub->is_Start() || sub->is_Root()) {
1288       // Success if we met 'dom' along a path to Start or Root.
1289       // We assume there are no alternative paths that avoid 'dom'.
1290       // (This assumption is up to the caller to ensure!)
1291       return met_dom;
1292     }
1293     Node* up = sub->in(0);
1294     // Normalize simple pass-through regions and projections:
1295     up = sub->find_exact_control(up);
1296     // If sub == up, we found a self-loop.  Try to push past it.
1297     if (sub == up && sub->is_Loop()) {
1298       // Take loop entry path on the way up to 'dom'.
1299       up = sub->in(1); // in(LoopNode::EntryControl);
1300     } else if (sub == up && sub->is_Region() && sub->req() == 2) {
1301       // Take in(1) path on the way up to 'dom' for regions with only one input
1302       up = sub->in(1);
1303     } else if (sub == up && sub->is_Region()) {
1304       // Try both paths for Regions with 2 input paths (it may be a loop head).
1305       // It could give conservative 'false' answer without information
1306       // which region's input is the entry path.
1307       iterations_without_region_limit = DominatorSearchLimit; // Reset
1308 
1309       bool region_was_visited_before = false;
1310       // Was this Region node visited before?
1311       // If so, we have reached it because we accidentally took a
1312       // loop-back edge from 'sub' back into the body of the loop,
1313       // and worked our way up again to the loop header 'sub'.
1314       // So, take the first unexplored path on the way up to 'dom'.
1315       for (int j = nlist.size() - 1; j >= 0; j--) {
1316         intptr_t ni = (intptr_t)nlist.at(j);
1317         Node* visited = (Node*)(ni & ~1);
1318         bool  visited_twice_already = ((ni & 1) != 0);
1319         if (visited == sub) {
1320           if (visited_twice_already) {
1321             // Visited 2 paths, but still stuck in loop body.  Give up.
1322             return false;
1323           }
1324           // The Region node was visited before only once.
1325           // (We will repush with the low bit set, below.)
1326           nlist.remove(j);
1327           // We will find a new edge and re-insert.
1328           region_was_visited_before = true;
1329           break;
1330         }
1331       }
1332 
1333       // Find an incoming edge which has not been seen yet; walk through it.
1334       assert(up == sub, "");
1335       uint skip = region_was_visited_before ? 1 : 0;
1336       for (uint i = 1; i < sub->req(); i++) {
1337         Node* in = sub->in(i);
1338         if (in != nullptr && !in->is_top() && in != sub) {
1339           if (skip == 0) {
1340             up = in;
1341             break;
1342           }
1343           --skip;               // skip this nontrivial input
1344         }
1345       }
1346 
1347       // Set 0 bit to indicate that both paths were taken.
1348       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1349     }
1350 
1351     if (up == sub) {
1352       break;    // some kind of tight cycle
1353     }
1354     if (up == orig_sub && met_dom) {
1355       // returned back after visiting 'dom'
1356       break;    // some kind of cycle
1357     }
1358     if (--iterations_without_region_limit < 0) {
1359       break;    // dead cycle
1360     }
1361     sub = up;
1362   }
1363 
1364   // Did not meet Root or Start node in pred. chain.
1365   // Conservative answer for dead code.
1366   return false;
1367 }
1368 
1369 //------------------------------remove_dead_region-----------------------------
1370 // This control node is dead.  Follow the subgraph below it making everything
1371 // using it dead as well.  This will happen normally via the usual IterGVN
1372 // worklist but this call is more efficient.  Do not update use-def info
1373 // inside the dead region, just at the borders.
1374 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1375   // Con's are a popular node to re-hit in the hash table again.
1376   if( dead->is_Con() ) return;
1377 
1378   ResourceMark rm;
1379   Node_List nstack;
1380   VectorSet dead_set; // notify uses only once
1381 
1382   Node *top = igvn->C->top();
1383   nstack.push(dead);
1384   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1385 
1386   while (nstack.size() > 0) {
1387     dead = nstack.pop();
1388     if (!dead_set.test_set(dead->_idx)) {
1389       // If dead has any live uses, those are now still attached. Notify them before we lose them.
1390       igvn->add_users_to_worklist(dead);
1391     }
1392     if (dead->Opcode() == Op_SafePoint) {
1393       dead->as_SafePoint()->disconnect_from_root(igvn);
1394     }
1395     if (dead->outcnt() > 0) {
1396       // Keep dead node on stack until all uses are processed.
1397       nstack.push(dead);
1398       // For all Users of the Dead...    ;-)
1399       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1400         Node* use = dead->last_out(k);
1401         igvn->hash_delete(use);       // Yank from hash table prior to mod
1402         if (use->in(0) == dead) {     // Found another dead node
1403           assert (!use->is_Con(), "Control for Con node should be Root node.");
1404           use->set_req(0, top);       // Cut dead edge to prevent processing
1405           nstack.push(use);           // the dead node again.
1406         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1407                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1408                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1409           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1410           use->set_req(0, top);       // Cut self edge
1411           nstack.push(use);
1412         } else {                      // Else found a not-dead user
1413           // Dead if all inputs are top or null
1414           bool dead_use = !use->is_Root(); // Keep empty graph alive
1415           for (uint j = 1; j < use->req(); j++) {
1416             Node* in = use->in(j);
1417             if (in == dead) {         // Turn all dead inputs into TOP
1418               use->set_req(j, top);
1419             } else if (in != nullptr && !in->is_top()) {
1420               dead_use = false;
1421             }
1422           }
1423           if (dead_use) {
1424             if (use->is_Region()) {
1425               use->set_req(0, top);   // Cut self edge
1426             }
1427             nstack.push(use);
1428           } else {
1429             igvn->_worklist.push(use);
1430           }
1431         }
1432         // Refresh the iterator, since any number of kills might have happened.
1433         k = dead->last_outs(kmin);
1434       }
1435     } else { // (dead->outcnt() == 0)
1436       // Done with outputs.
1437       igvn->hash_delete(dead);
1438       igvn->_worklist.remove(dead);
1439       igvn->set_type(dead, Type::TOP);
1440       // Kill all inputs to the dead guy
1441       for (uint i=0; i < dead->req(); i++) {
1442         Node *n = dead->in(i);      // Get input to dead guy
1443         if (n != nullptr && !n->is_top()) { // Input is valid?
1444           dead->set_req(i, top);    // Smash input away
1445           if (n->outcnt() == 0) {   // Input also goes dead?
1446             if (!n->is_Con())
1447               nstack.push(n);       // Clear it out as well
1448           } else if (n->outcnt() == 1 &&
1449                      n->has_special_unique_user()) {
1450             igvn->add_users_to_worklist( n );
1451           } else if (n->outcnt() <= 2 && n->is_Store()) {
1452             // Push store's uses on worklist to enable folding optimization for
1453             // store/store and store/load to the same address.
1454             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1455             // and remove_globally_dead_node().
1456             igvn->add_users_to_worklist( n );
1457           } else {
1458             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
1459           }
1460         }
1461       }
1462       igvn->C->remove_useless_node(dead);
1463     } // (dead->outcnt() == 0)
1464   }   // while (nstack.size() > 0) for outputs
1465   return;
1466 }
1467 
1468 //------------------------------remove_dead_region-----------------------------
1469 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1470   Node *n = in(0);
1471   if( !n ) return false;
1472   // Lost control into this guy?  I.e., it became unreachable?
1473   // Aggressively kill all unreachable code.
1474   if (can_reshape && n->is_top()) {
1475     kill_dead_code(this, phase->is_IterGVN());
1476     return false; // Node is dead.
1477   }
1478 
1479   if( n->is_Region() && n->as_Region()->is_copy() ) {
1480     Node *m = n->nonnull_req();
1481     set_req(0, m);
1482     return true;
1483   }
1484   return false;
1485 }
1486 
1487 //------------------------------hash-------------------------------------------
1488 // Hash function over Nodes.
1489 uint Node::hash() const {
1490   uint sum = 0;
1491   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1492     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded nulls
1493   return (sum>>2) + _cnt + Opcode();
1494 }
1495 
1496 //------------------------------cmp--------------------------------------------
1497 // Compare special parts of simple Nodes
1498 bool Node::cmp( const Node &n ) const {
1499   return true;                  // Must be same
1500 }
1501 
1502 //------------------------------rematerialize-----------------------------------
1503 // Should we clone rather than spill this instruction?
1504 bool Node::rematerialize() const {
1505   if ( is_Mach() )
1506     return this->as_Mach()->rematerialize();
1507   else
1508     return (_flags & Flag_rematerialize) != 0;
1509 }
1510 
1511 //------------------------------needs_anti_dependence_check---------------------
1512 // Nodes which use memory without consuming it, hence need antidependences.
1513 bool Node::needs_anti_dependence_check() const {
1514   if (req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0) {
1515     return false;
1516   }
1517   return in(1)->bottom_type()->has_memory();
1518 }
1519 
1520 // Get an integer constant from a ConNode (or CastIINode).
1521 // Return a default value if there is no apparent constant here.
1522 const TypeInt* Node::find_int_type() const {
1523   if (this->is_Type()) {
1524     return this->as_Type()->type()->isa_int();
1525   } else if (this->is_Con()) {
1526     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1527     return this->bottom_type()->isa_int();
1528   }
1529   return nullptr;
1530 }
1531 
1532 const TypeInteger* Node::find_integer_type(BasicType bt) const {
1533   if (this->is_Type()) {
1534     return this->as_Type()->type()->isa_integer(bt);
1535   } else if (this->is_Con()) {
1536     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1537     return this->bottom_type()->isa_integer(bt);
1538   }
1539   return nullptr;
1540 }
1541 
1542 // Get a pointer constant from a ConstNode.
1543 // Returns the constant if it is a pointer ConstNode
1544 intptr_t Node::get_ptr() const {
1545   assert( Opcode() == Op_ConP, "" );
1546   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1547 }
1548 
1549 // Get a narrow oop constant from a ConNNode.
1550 intptr_t Node::get_narrowcon() const {
1551   assert( Opcode() == Op_ConN, "" );
1552   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1553 }
1554 
1555 // Get a long constant from a ConNode.
1556 // Return a default value if there is no apparent constant here.
1557 const TypeLong* Node::find_long_type() const {
1558   if (this->is_Type()) {
1559     return this->as_Type()->type()->isa_long();
1560   } else if (this->is_Con()) {
1561     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1562     return this->bottom_type()->isa_long();
1563   }
1564   return nullptr;
1565 }
1566 
1567 
1568 /**
1569  * Return a ptr type for nodes which should have it.
1570  */
1571 const TypePtr* Node::get_ptr_type() const {
1572   const TypePtr* tp = this->bottom_type()->make_ptr();
1573 #ifdef ASSERT
1574   if (tp == nullptr) {
1575     this->dump(1);
1576     assert((tp != nullptr), "unexpected node type");
1577   }
1578 #endif
1579   return tp;
1580 }
1581 
1582 // Get a double constant from a ConstNode.
1583 // Returns the constant if it is a double ConstNode
1584 jdouble Node::getd() const {
1585   assert( Opcode() == Op_ConD, "" );
1586   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1587 }
1588 
1589 // Get a float constant from a ConstNode.
1590 // Returns the constant if it is a float ConstNode
1591 jfloat Node::getf() const {
1592   assert( Opcode() == Op_ConF, "" );
1593   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1594 }
1595 
1596 #ifndef PRODUCT
1597 
1598 // Call this from debugger:
1599 Node* old_root() {
1600   Matcher* matcher = Compile::current()->matcher();
1601   if (matcher != nullptr) {
1602     Node* new_root = Compile::current()->root();
1603     Node* old_root = matcher->find_old_node(new_root);
1604     if (old_root != nullptr) {
1605       return old_root;
1606     }
1607   }
1608   tty->print("old_root: not found.\n");
1609   return nullptr;
1610 }
1611 
1612 // BFS traverse all reachable nodes from start, call callback on them
1613 template <typename Callback>
1614 void visit_nodes(Node* start, Callback callback, bool traverse_output, bool only_ctrl) {
1615   Unique_Mixed_Node_List worklist;
1616   worklist.add(start);
1617   for (uint i = 0; i < worklist.size(); i++) {
1618     Node* n = worklist[i];
1619     callback(n);
1620     for (uint i = 0; i < n->len(); i++) {
1621       if (!only_ctrl || n->is_Region() || (n->Opcode() == Op_Root) || (i == TypeFunc::Control)) {
1622         // If only_ctrl is set: Add regions, the root node, or control inputs only
1623         worklist.add(n->in(i));
1624       }
1625     }
1626     if (traverse_output && !only_ctrl) {
1627       for (uint i = 0; i < n->outcnt(); i++) {
1628         worklist.add(n->raw_out(i));
1629       }
1630     }
1631   }
1632 }
1633 
1634 // BFS traverse from start, return node with idx
1635 Node* find_node_by_idx(Node* start, uint idx, bool traverse_output, bool only_ctrl) {
1636   ResourceMark rm;
1637   Node* result = nullptr;
1638   auto callback = [&] (Node* n) {
1639     if (n->_idx == idx) {
1640       if (result != nullptr) {
1641         tty->print("find_node_by_idx: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1642           (uintptr_t)result, (uintptr_t)n, idx);
1643       }
1644       result = n;
1645     }
1646   };
1647   visit_nodes(start, callback, traverse_output, only_ctrl);
1648   return result;
1649 }
1650 
1651 int node_idx_cmp(const Node** n1, const Node** n2) {
1652   return (*n1)->_idx - (*n2)->_idx;
1653 }
1654 
1655 void find_nodes_by_name(Node* start, const char* name) {
1656   ResourceMark rm;
1657   GrowableArray<const Node*> ns;
1658   auto callback = [&] (const Node* n) {
1659     if (StringUtils::is_star_match(name, n->Name())) {
1660       ns.push(n);
1661     }
1662   };
1663   visit_nodes(start, callback, true, false);
1664   ns.sort(node_idx_cmp);
1665   for (int i = 0; i < ns.length(); i++) {
1666     ns.at(i)->dump();
1667   }
1668 }
1669 
1670 void find_nodes_by_dump(Node* start, const char* pattern) {
1671   ResourceMark rm;
1672   GrowableArray<const Node*> ns;
1673   auto callback = [&] (const Node* n) {
1674     stringStream stream;
1675     n->dump("", false, &stream);
1676     if (StringUtils::is_star_match(pattern, stream.base())) {
1677       ns.push(n);
1678     }
1679   };
1680   visit_nodes(start, callback, true, false);
1681   ns.sort(node_idx_cmp);
1682   for (int i = 0; i < ns.length(); i++) {
1683     ns.at(i)->dump();
1684   }
1685 }
1686 
1687 // call from debugger: find node with name pattern in new/current graph
1688 // name can contain "*" in match pattern to match any characters
1689 // the matching is case insensitive
1690 void find_nodes_by_name(const char* name) {
1691   Node* root = Compile::current()->root();
1692   find_nodes_by_name(root, name);
1693 }
1694 
1695 // call from debugger: find node with name pattern in old graph
1696 // name can contain "*" in match pattern to match any characters
1697 // the matching is case insensitive
1698 void find_old_nodes_by_name(const char* name) {
1699   Node* root = old_root();
1700   find_nodes_by_name(root, name);
1701 }
1702 
1703 // call from debugger: find node with dump pattern in new/current graph
1704 // can contain "*" in match pattern to match any characters
1705 // the matching is case insensitive
1706 void find_nodes_by_dump(const char* pattern) {
1707   Node* root = Compile::current()->root();
1708   find_nodes_by_dump(root, pattern);
1709 }
1710 
1711 // call from debugger: find node with name pattern in old graph
1712 // can contain "*" in match pattern to match any characters
1713 // the matching is case insensitive
1714 void find_old_nodes_by_dump(const char* pattern) {
1715   Node* root = old_root();
1716   find_nodes_by_dump(root, pattern);
1717 }
1718 
1719 // Call this from debugger, search in same graph as n:
1720 Node* find_node(Node* n, const int idx) {
1721   return n->find(idx);
1722 }
1723 
1724 // Call this from debugger, search in new nodes:
1725 Node* find_node(const int idx) {
1726   return Compile::current()->root()->find(idx);
1727 }
1728 
1729 // Call this from debugger, search in old nodes:
1730 Node* find_old_node(const int idx) {
1731   Node* root = old_root();
1732   return (root == nullptr) ? nullptr : root->find(idx);
1733 }
1734 
1735 // Call this from debugger, search in same graph as n:
1736 Node* find_ctrl(Node* n, const int idx) {
1737   return n->find_ctrl(idx);
1738 }
1739 
1740 // Call this from debugger, search in new nodes:
1741 Node* find_ctrl(const int idx) {
1742   return Compile::current()->root()->find_ctrl(idx);
1743 }
1744 
1745 // Call this from debugger, search in old nodes:
1746 Node* find_old_ctrl(const int idx) {
1747   Node* root = old_root();
1748   return (root == nullptr) ? nullptr : root->find_ctrl(idx);
1749 }
1750 
1751 //------------------------------find_ctrl--------------------------------------
1752 // Find an ancestor to this node in the control history with given _idx
1753 Node* Node::find_ctrl(int idx) {
1754   return find(idx, true);
1755 }
1756 
1757 //------------------------------find-------------------------------------------
1758 // Tries to find the node with the index |idx| starting from this node. If idx is negative,
1759 // the search also includes forward (out) edges. Returns null if not found.
1760 // If only_ctrl is set, the search will only be done on control nodes. Returns null if
1761 // not found or if the node to be found is not a control node (search will not find it).
1762 Node* Node::find(const int idx, bool only_ctrl) {
1763   ResourceMark rm;
1764   return find_node_by_idx(this, abs(idx), (idx < 0), only_ctrl);
1765 }
1766 
1767 class PrintBFS {
1768 public:
1769   PrintBFS(const Node* start, const int max_distance, const Node* target, const char* options, outputStream* st)
1770   : _start(start), _max_distance(max_distance), _target(target), _options(options), _output(st),
1771     _dcc(this), _info_uid(cmpkey, hashkey) {}
1772 
1773   void run();
1774 private:
1775   // pipeline steps
1776   bool configure();
1777   void collect();
1778   void select();
1779   void select_all();
1780   void select_all_paths();
1781   void select_shortest_path();
1782   void sort();
1783   void print();
1784 
1785   // inputs
1786   const Node* _start;
1787   const int _max_distance;
1788   const Node* _target;
1789   const char* _options;
1790   outputStream* _output;
1791 
1792   // options
1793   bool _traverse_inputs = false;
1794   bool _traverse_outputs = false;
1795   struct Filter {
1796     bool _control = false;
1797     bool _memory = false;
1798     bool _data = false;
1799     bool _mixed = false;
1800     bool _other = false;
1801     bool is_empty() const {
1802       return !(_control || _memory || _data || _mixed || _other);
1803     }
1804     void set_all() {
1805       _control = true;
1806       _memory = true;
1807       _data = true;
1808       _mixed = true;
1809       _other = true;
1810     }
1811     // Check if the filter accepts the node. Go by the type categories, but also all CFG nodes
1812     // are considered to have control.
1813     bool accepts(const Node* n) {
1814       const Type* t = n->bottom_type();
1815       return ( _data    &&  t->has_category(Type::Category::Data)                    ) ||
1816              ( _memory  &&  t->has_category(Type::Category::Memory)                  ) ||
1817              ( _mixed   &&  t->has_category(Type::Category::Mixed)                   ) ||
1818              ( _control && (t->has_category(Type::Category::Control) || n->is_CFG()) ) ||
1819              ( _other   &&  t->has_category(Type::Category::Other)                   );
1820     }
1821   };
1822   Filter _filter_visit;
1823   Filter _filter_boundary;
1824   bool _sort_idx = false;
1825   bool _all_paths = false;
1826   bool _use_color = false;
1827   bool _print_blocks = false;
1828   bool _print_old = false;
1829   bool _dump_only = false;
1830   void print_options_help(bool print_examples);
1831   bool parse_options();
1832 
1833 public:
1834   class DumpConfigColored : public Node::DumpConfig {
1835   public:
1836     DumpConfigColored(PrintBFS* bfs) : _bfs(bfs) {};
1837     virtual void pre_dump(outputStream* st, const Node* n);
1838     virtual void post_dump(outputStream* st);
1839   private:
1840     PrintBFS* _bfs;
1841   };
1842 private:
1843   DumpConfigColored _dcc;
1844 
1845   // node info
1846   static Node* old_node(const Node* n); // mach node -> prior IR node
1847   void print_node_idx(const Node* n);
1848   void print_block_id(const Block* b);
1849   void print_node_block(const Node* n); // _pre_order, head idx, _idom, _dom_depth
1850 
1851   // traversal data structures
1852   GrowableArray<const Node*> _worklist; // BFS queue
1853   void maybe_traverse(const Node* src, const Node* dst);
1854 
1855   // node info annotation
1856   class Info {
1857   public:
1858     Info() : Info(nullptr, 0) {};
1859     Info(const Node* node, int distance)
1860       : _node(node), _distance_from_start(distance) {};
1861     const Node* node() const { return _node; };
1862     int distance() const { return _distance_from_start; };
1863     int distance_from_target() const { return _distance_from_target; }
1864     void set_distance_from_target(int d) { _distance_from_target = d; }
1865     GrowableArray<const Node*> edge_bwd; // pointing toward _start
1866     bool is_marked() const { return _mark; } // marked to keep during select
1867     void set_mark() { _mark = true; }
1868   private:
1869     const Node* _node;
1870     int _distance_from_start; // distance from _start
1871     int _distance_from_target = 0; // distance from _target if _all_paths
1872     bool _mark = false;
1873   };
1874   Dict _info_uid;            // Node -> uid
1875   GrowableArray<Info> _info; // uid  -> info
1876 
1877   Info* find_info(const Node* n) {
1878     size_t uid = (size_t)_info_uid[n];
1879     if (uid == 0) {
1880       return nullptr;
1881     }
1882     return &_info.at((int)uid);
1883   }
1884 
1885   void make_info(const Node* node, const int distance) {
1886     assert(find_info(node) == nullptr, "node does not yet have info");
1887     size_t uid = _info.length() + 1;
1888     _info_uid.Insert((void*)node, (void*)uid);
1889     _info.at_put_grow((int)uid, Info(node, distance));
1890     assert(find_info(node)->node() == node, "stored correct node");
1891   };
1892 
1893   // filled by sort, printed by print
1894   GrowableArray<const Node*> _print_list;
1895 
1896   // print header + node table
1897   void print_header() const;
1898   void print_node(const Node* n);
1899 };
1900 
1901 void PrintBFS::run() {
1902   if (!configure()) {
1903     return;
1904   }
1905   collect();
1906   select();
1907   sort();
1908   print();
1909 }
1910 
1911 // set up configuration for BFS and print
1912 bool PrintBFS::configure() {
1913   if (_max_distance < 0) {
1914     _output->print_cr("dump_bfs: max_distance must be non-negative!");
1915     return false;
1916   }
1917   return parse_options();
1918 }
1919 
1920 // BFS traverse according to configuration, fill worklist and info
1921 void PrintBFS::collect() {
1922   maybe_traverse(_start, _start);
1923   int pos = 0;
1924   while (pos < _worklist.length()) {
1925     const Node* n = _worklist.at(pos++); // next node to traverse
1926     Info* info = find_info(n);
1927     if (!_filter_visit.accepts(n) && n != _start) {
1928       continue; // we hit boundary, do not traverse further
1929     }
1930     if (n != _start && n->is_Root()) {
1931       continue; // traversing through root node would lead to unrelated nodes
1932     }
1933     if (_traverse_inputs && _max_distance > info->distance()) {
1934       for (uint i = 0; i < n->req(); i++) {
1935         maybe_traverse(n, n->in(i));
1936       }
1937     }
1938     if (_traverse_outputs && _max_distance > info->distance()) {
1939       for (uint i = 0; i < n->outcnt(); i++) {
1940         maybe_traverse(n, n->raw_out(i));
1941       }
1942     }
1943   }
1944 }
1945 
1946 // go through work list, mark those that we want to print
1947 void PrintBFS::select() {
1948   if (_target == nullptr ) {
1949     select_all();
1950   } else {
1951     if (find_info(_target) == nullptr) {
1952       _output->print_cr("Could not find target in BFS.");
1953       return;
1954     }
1955     if (_all_paths) {
1956       select_all_paths();
1957     } else {
1958       select_shortest_path();
1959     }
1960   }
1961 }
1962 
1963 // take all nodes from BFS
1964 void PrintBFS::select_all() {
1965   for (int i = 0; i < _worklist.length(); i++) {
1966     const Node* n = _worklist.at(i);
1967     Info* info = find_info(n);
1968     info->set_mark();
1969   }
1970 }
1971 
1972 // traverse backward from target, along edges found in BFS
1973 void PrintBFS::select_all_paths() {
1974   int pos = 0;
1975   GrowableArray<const Node*> backtrace;
1976   // start from target
1977   backtrace.push(_target);
1978   find_info(_target)->set_mark();
1979   // traverse backward
1980   while (pos < backtrace.length()) {
1981     const Node* n = backtrace.at(pos++);
1982     Info* info = find_info(n);
1983     for (int i = 0; i < info->edge_bwd.length(); i++) {
1984       // all backward edges
1985       const Node* back = info->edge_bwd.at(i);
1986       Info* back_info = find_info(back);
1987       if (!back_info->is_marked()) {
1988         // not yet found this on way back.
1989         back_info->set_distance_from_target(info->distance_from_target() + 1);
1990         if (back_info->distance_from_target() + back_info->distance() <= _max_distance) {
1991           // total distance is small enough
1992           back_info->set_mark();
1993           backtrace.push(back);
1994         }
1995       }
1996     }
1997   }
1998 }
1999 
2000 void PrintBFS::select_shortest_path() {
2001   const Node* current = _target;
2002   while (true) {
2003     Info* info = find_info(current);
2004     info->set_mark();
2005     if (current == _start) {
2006       break;
2007     }
2008     // first edge -> leads us one step closer to _start
2009     current = info->edge_bwd.at(0);
2010   }
2011 }
2012 
2013 // go through worklist in desired order, put the marked ones in print list
2014 void PrintBFS::sort() {
2015   if (_traverse_inputs && !_traverse_outputs) {
2016     // reverse order
2017     for (int i = _worklist.length() - 1; i >= 0; i--) {
2018       const Node* n = _worklist.at(i);
2019       Info* info = find_info(n);
2020       if (info->is_marked()) {
2021         _print_list.push(n);
2022       }
2023     }
2024   } else {
2025     // same order as worklist
2026     for (int i = 0; i < _worklist.length(); i++) {
2027       const Node* n = _worklist.at(i);
2028       Info* info = find_info(n);
2029       if (info->is_marked()) {
2030         _print_list.push(n);
2031       }
2032     }
2033   }
2034   if (_sort_idx) {
2035     _print_list.sort(node_idx_cmp);
2036   }
2037 }
2038 
2039 // go through printlist and print
2040 void PrintBFS::print() {
2041   if (_print_list.length() > 0 ) {
2042     print_header();
2043     for (int i = 0; i < _print_list.length(); i++) {
2044       const Node* n = _print_list.at(i);
2045       print_node(n);
2046     }
2047   } else {
2048     _output->print_cr("No nodes to print.");
2049   }
2050 }
2051 
2052 void PrintBFS::print_options_help(bool print_examples) {
2053   _output->print_cr("Usage: node->dump_bfs(int max_distance, Node* target, char* options)");
2054   _output->print_cr("");
2055   _output->print_cr("Use cases:");
2056   _output->print_cr("  BFS traversal: no target required");
2057   _output->print_cr("  shortest path: set target");
2058   _output->print_cr("  all paths: set target and put 'A' in options");
2059   _output->print_cr("  detect loop: subcase of all paths, have start==target");
2060   _output->print_cr("");
2061   _output->print_cr("Arguments:");
2062   _output->print_cr("  this/start: staring point of BFS");
2063   _output->print_cr("  target:");
2064   _output->print_cr("    if null: simple BFS");
2065   _output->print_cr("    else: shortest path or all paths between this/start and target");
2066   _output->print_cr("  options:");
2067   _output->print_cr("    if null: same as \"cdmox@B\"");
2068   _output->print_cr("    else: use combination of following characters");
2069   _output->print_cr("      h: display this help info");
2070   _output->print_cr("      H: display this help info, with examples");
2071   _output->print_cr("      +: traverse in-edges (on if neither + nor -)");
2072   _output->print_cr("      -: traverse out-edges");
2073   _output->print_cr("      c: visit control nodes");
2074   _output->print_cr("      d: visit data nodes");
2075   _output->print_cr("      m: visit memory nodes");
2076   _output->print_cr("      o: visit other nodes");
2077   _output->print_cr("      x: visit mixed nodes");
2078   _output->print_cr("      C: boundary control nodes");
2079   _output->print_cr("      D: boundary data nodes");
2080   _output->print_cr("      M: boundary memory nodes");
2081   _output->print_cr("      O: boundary other nodes");
2082   _output->print_cr("      X: boundary mixed nodes");
2083   _output->print_cr("      #: display node category in color (not supported in all terminals)");
2084   _output->print_cr("      S: sort displayed nodes by node idx");
2085   _output->print_cr("      A: all paths (not just shortest path to target)");
2086   _output->print_cr("      @: print old nodes - before matching (if available)");
2087   _output->print_cr("      B: print scheduling blocks (if available)");
2088   _output->print_cr("      $: dump only, no header, no other columns");
2089   _output->print_cr("");
2090   _output->print_cr("recursively follow edges to nodes with permitted visit types,");
2091   _output->print_cr("on the boundary additionally display nodes allowed in boundary types");
2092   _output->print_cr("Note: the categories can be overlapping. For example a mixed node");
2093   _output->print_cr("      can contain control and memory output. Some from the other");
2094   _output->print_cr("      category are also control (Halt, Return, etc).");
2095   _output->print_cr("");
2096   _output->print_cr("output columns:");
2097   _output->print_cr("  dist:  BFS distance to this/start");
2098   _output->print_cr("  apd:   all paths distance (d_outputart + d_target)");
2099   _output->print_cr("  block: block identifier, based on _pre_order");
2100   _output->print_cr("  head:  first node in block");
2101   _output->print_cr("  idom:  head node of idom block");
2102   _output->print_cr("  depth: depth of block (_dom_depth)");
2103   _output->print_cr("  old:   old IR node - before matching");
2104   _output->print_cr("  dump:  node->dump()");
2105   _output->print_cr("");
2106   _output->print_cr("Note: if none of the \"cmdxo\" characters are in the options string");
2107   _output->print_cr("      then we set all of them.");
2108   _output->print_cr("      This allows for short strings like \"#\" for colored input traversal");
2109   _output->print_cr("      or \"-#\" for colored output traversal.");
2110   if (print_examples) {
2111     _output->print_cr("");
2112     _output->print_cr("Examples:");
2113     _output->print_cr("  if->dump_bfs(10, 0, \"+cxo\")");
2114     _output->print_cr("    starting at some if node, traverse inputs recursively");
2115     _output->print_cr("    only along control (mixed and other can also be control)");
2116     _output->print_cr("  phi->dump_bfs(5, 0, \"-dxo\")");
2117     _output->print_cr("    starting at phi node, traverse outputs recursively");
2118     _output->print_cr("    only along data (mixed and other can also have data flow)");
2119     _output->print_cr("  find_node(385)->dump_bfs(3, 0, \"cdmox+#@B\")");
2120     _output->print_cr("    find inputs of node 385, up to 3 nodes up (+)");
2121     _output->print_cr("    traverse all nodes (cdmox), use colors (#)");
2122     _output->print_cr("    display old nodes and blocks, if they exist");
2123     _output->print_cr("    useful call to start with");
2124     _output->print_cr("  find_node(102)->dump_bfs(10, 0, \"dCDMOX-\")");
2125     _output->print_cr("    find non-data dependencies of a data node");
2126     _output->print_cr("    follow data node outputs until we find another category");
2127     _output->print_cr("    node as the boundary");
2128     _output->print_cr("  x->dump_bfs(10, y, 0)");
2129     _output->print_cr("    find shortest path from x to y, along any edge or node");
2130     _output->print_cr("    will not find a path if it is longer than 10");
2131     _output->print_cr("    useful to find how x and y are related");
2132     _output->print_cr("  find_node(741)->dump_bfs(20, find_node(746), \"c+\")");
2133     _output->print_cr("    find shortest control path between two nodes");
2134     _output->print_cr("  find_node(741)->dump_bfs(8, find_node(746), \"cdmox+A\")");
2135     _output->print_cr("    find all paths (A) between two nodes of length at most 8");
2136     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A\")");
2137     _output->print_cr("    find all control loops for this node");
2138   }
2139 }
2140 
2141 bool PrintBFS::parse_options() {
2142   if (_options == nullptr) {
2143     _options = "cdmox@B"; // default options
2144   }
2145   size_t len = strlen(_options);
2146   for (size_t i = 0; i < len; i++) {
2147     switch (_options[i]) {
2148       case '+':
2149         _traverse_inputs = true;
2150         break;
2151       case '-':
2152         _traverse_outputs = true;
2153         break;
2154       case 'c':
2155         _filter_visit._control = true;
2156         break;
2157       case 'm':
2158         _filter_visit._memory = true;
2159         break;
2160       case 'd':
2161         _filter_visit._data = true;
2162         break;
2163       case 'x':
2164         _filter_visit._mixed = true;
2165         break;
2166       case 'o':
2167         _filter_visit._other = true;
2168         break;
2169       case 'C':
2170         _filter_boundary._control = true;
2171         break;
2172       case 'M':
2173         _filter_boundary._memory = true;
2174         break;
2175       case 'D':
2176         _filter_boundary._data = true;
2177         break;
2178       case 'X':
2179         _filter_boundary._mixed = true;
2180         break;
2181       case 'O':
2182         _filter_boundary._other = true;
2183         break;
2184       case 'S':
2185         _sort_idx = true;
2186         break;
2187       case 'A':
2188         _all_paths = true;
2189         break;
2190       case '#':
2191         _use_color = true;
2192         break;
2193       case 'B':
2194         _print_blocks = true;
2195         break;
2196       case '@':
2197         _print_old = true;
2198         break;
2199       case '$':
2200         _dump_only = true;
2201         break;
2202       case 'h':
2203         print_options_help(false);
2204         return false;
2205        case 'H':
2206         print_options_help(true);
2207         return false;
2208       default:
2209         _output->print_cr("dump_bfs: Unrecognized option \'%c\'", _options[i]);
2210         _output->print_cr("for help, run: find_node(0)->dump_bfs(0,0,\"H\")");
2211         return false;
2212     }
2213   }
2214   if (!_traverse_inputs && !_traverse_outputs) {
2215     _traverse_inputs = true;
2216   }
2217   if (_filter_visit.is_empty()) {
2218     _filter_visit.set_all();
2219   }
2220   Compile* C = Compile::current();
2221   _print_old &= (C->matcher() != nullptr); // only show old if there are new
2222   _print_blocks &= (C->cfg() != nullptr); // only show blocks if available
2223   return true;
2224 }
2225 
2226 void PrintBFS::DumpConfigColored::pre_dump(outputStream* st, const Node* n) {
2227   if (!_bfs->_use_color) {
2228     return;
2229   }
2230   Info* info = _bfs->find_info(n);
2231   if (info == nullptr || !info->is_marked()) {
2232     return;
2233   }
2234 
2235   const Type* t = n->bottom_type();
2236   switch (t->category()) {
2237     case Type::Category::Data:
2238       st->print("\u001b[34m");
2239       break;
2240     case Type::Category::Memory:
2241       st->print("\u001b[32m");
2242       break;
2243     case Type::Category::Mixed:
2244       st->print("\u001b[35m");
2245       break;
2246     case Type::Category::Control:
2247       st->print("\u001b[31m");
2248       break;
2249     case Type::Category::Other:
2250       st->print("\u001b[33m");
2251       break;
2252     case Type::Category::Undef:
2253       n->dump();
2254       assert(false, "category undef ??");
2255       break;
2256     default:
2257       n->dump();
2258       assert(false, "not covered");
2259       break;
2260   }
2261 }
2262 
2263 void PrintBFS::DumpConfigColored::post_dump(outputStream* st) {
2264   if (!_bfs->_use_color) {
2265     return;
2266   }
2267   st->print("\u001b[0m"); // white
2268 }
2269 
2270 Node* PrintBFS::old_node(const Node* n) {
2271   Compile* C = Compile::current();
2272   if (C->matcher() == nullptr || !C->node_arena()->contains(n)) {
2273     return (Node*)nullptr;
2274   } else {
2275     return C->matcher()->find_old_node(n);
2276   }
2277 }
2278 
2279 void PrintBFS::print_node_idx(const Node* n) {
2280   Compile* C = Compile::current();
2281   char buf[30];
2282   if (n == nullptr) {
2283     os::snprintf_checked(buf, sizeof(buf), "_");           // null
2284   } else if (C->node_arena()->contains(n)) {
2285     os::snprintf_checked(buf, sizeof(buf), "%d", n->_idx);  // new node
2286   } else {
2287     os::snprintf_checked(buf, sizeof(buf), "o%d", n->_idx); // old node
2288   }
2289   _output->print("%6s", buf);
2290 }
2291 
2292 void PrintBFS::print_block_id(const Block* b) {
2293   Compile* C = Compile::current();
2294   char buf[30];
2295   os::snprintf_checked(buf, sizeof(buf), "B%d", b->_pre_order);
2296   _output->print("%7s", buf);
2297 }
2298 
2299 void PrintBFS::print_node_block(const Node* n) {
2300   Compile* C = Compile::current();
2301   Block* b = C->node_arena()->contains(n)
2302              ? C->cfg()->get_block_for_node(n)
2303              : nullptr; // guard against old nodes
2304   if (b == nullptr) {
2305     _output->print("      _"); // Block
2306     _output->print("     _");  // head
2307     _output->print("     _");  // idom
2308     _output->print("      _"); // depth
2309   } else {
2310     print_block_id(b);
2311     print_node_idx(b->head());
2312     if (b->_idom) {
2313       print_node_idx(b->_idom->head());
2314     } else {
2315       _output->print("     _"); // idom
2316     }
2317     _output->print("%6d ", b->_dom_depth);
2318   }
2319 }
2320 
2321 // filter, and add to worklist, add info, note traversal edges
2322 void PrintBFS::maybe_traverse(const Node* src, const Node* dst) {
2323   if (dst != nullptr &&
2324      (_filter_visit.accepts(dst) ||
2325       _filter_boundary.accepts(dst) ||
2326       dst == _start)) { // correct category or start?
2327     if (find_info(dst) == nullptr) {
2328       // never visited - set up info
2329       _worklist.push(dst);
2330       int d = 0;
2331       if (dst != _start) {
2332         d = find_info(src)->distance() + 1;
2333       }
2334       make_info(dst, d);
2335     }
2336     if (src != dst) {
2337       // traversal edges useful during select
2338       find_info(dst)->edge_bwd.push(src);
2339     }
2340   }
2341 }
2342 
2343 void PrintBFS::print_header() const {
2344   if (_dump_only) {
2345     return; // no header in dump only mode
2346   }
2347   _output->print("dist");                         // distance
2348   if (_all_paths) {
2349     _output->print(" apd");                       // all paths distance
2350   }
2351   if (_print_blocks) {
2352     _output->print(" [block  head  idom depth]"); // block
2353   }
2354   if (_print_old) {
2355     _output->print("   old");                     // old node
2356   }
2357   _output->print(" dump\n");                      // node dump
2358   _output->print_cr("---------------------------------------------");
2359 }
2360 
2361 void PrintBFS::print_node(const Node* n) {
2362   if (_dump_only) {
2363     n->dump("\n", false, _output, &_dcc);
2364     return;
2365   }
2366   _output->print("%4d", find_info(n)->distance());// distance
2367   if (_all_paths) {
2368     Info* info = find_info(n);
2369     int apd = info->distance() + info->distance_from_target();
2370     _output->print("%4d", apd);                   // all paths distance
2371   }
2372   if (_print_blocks) {
2373     print_node_block(n);                          // block
2374   }
2375   if (_print_old) {
2376     print_node_idx(old_node(n));                  // old node
2377   }
2378   _output->print(" ");
2379   n->dump("\n", false, _output, &_dcc);           // node dump
2380 }
2381 
2382 //------------------------------dump_bfs--------------------------------------
2383 // Call this from debugger
2384 // Useful for BFS traversal, shortest path, all path, loop detection, etc
2385 // Designed to be more readable, and provide additional info
2386 // To find all options, run:
2387 //   find_node(0)->dump_bfs(0,0,"H")
2388 void Node::dump_bfs(const int max_distance, Node* target, const char* options) const {
2389   dump_bfs(max_distance, target, options, tty);
2390 }
2391 
2392 // Used to dump to stream.
2393 void Node::dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st) const {
2394   PrintBFS bfs(this, max_distance, target, options, st);
2395   bfs.run();
2396 }
2397 
2398 // Call this from debugger, with default arguments
2399 void Node::dump_bfs(const int max_distance) const {
2400   dump_bfs(max_distance, nullptr, nullptr);
2401 }
2402 
2403 // -----------------------------dump_idx---------------------------------------
2404 void Node::dump_idx(bool align, outputStream* st, DumpConfig* dc) const {
2405   if (dc != nullptr) {
2406     dc->pre_dump(st, this);
2407   }
2408   Compile* C = Compile::current();
2409   bool is_new = C->node_arena()->contains(this);
2410   if (align) { // print prefix empty spaces$
2411     // +1 for leading digit, +1 for "o"
2412     uint max_width = static_cast<uint>(log10(static_cast<double>(C->unique()))) + 2;
2413     // +1 for leading digit, maybe +1 for "o"
2414     uint width = static_cast<uint>(log10(static_cast<double>(_idx))) + 1 + (is_new ? 0 : 1);
2415     while (max_width > width) {
2416       st->print(" ");
2417       width++;
2418     }
2419   }
2420   if (!is_new) {
2421     st->print("o");
2422   }
2423   st->print("%d", _idx);
2424   if (dc != nullptr) {
2425     dc->post_dump(st);
2426   }
2427 }
2428 
2429 // -----------------------------dump_name--------------------------------------
2430 void Node::dump_name(outputStream* st, DumpConfig* dc) const {
2431   if (dc != nullptr) {
2432     dc->pre_dump(st, this);
2433   }
2434   st->print("%s", Name());
2435   if (dc != nullptr) {
2436     dc->post_dump(st);
2437   }
2438 }
2439 
2440 // -----------------------------Name-------------------------------------------
2441 extern const char *NodeClassNames[];
2442 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
2443 
2444 static bool is_disconnected(const Node* n) {
2445   for (uint i = 0; i < n->req(); i++) {
2446     if (n->in(i) != nullptr)  return false;
2447   }
2448   return true;
2449 }
2450 
2451 #ifdef ASSERT
2452 void Node::dump_orig(outputStream *st, bool print_key) const {
2453   Compile* C = Compile::current();
2454   Node* orig = _debug_orig;
2455   if (not_a_node(orig)) orig = nullptr;
2456   if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2457   if (orig == nullptr) return;
2458   if (print_key) {
2459     st->print(" !orig=");
2460   }
2461   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
2462   if (not_a_node(fast)) fast = nullptr;
2463   while (orig != nullptr) {
2464     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
2465     if (discon) st->print("[");
2466     if (!Compile::current()->node_arena()->contains(orig))
2467       st->print("o");
2468     st->print("%d", orig->_idx);
2469     if (discon) st->print("]");
2470     orig = orig->debug_orig();
2471     if (not_a_node(orig)) orig = nullptr;
2472     if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2473     if (orig != nullptr) st->print(",");
2474     if (fast != nullptr) {
2475       // Step fast twice for each single step of orig:
2476       fast = fast->debug_orig();
2477       if (not_a_node(fast)) fast = nullptr;
2478       if (fast != nullptr && fast != orig) {
2479         fast = fast->debug_orig();
2480         if (not_a_node(fast)) fast = nullptr;
2481       }
2482       if (fast == orig) {
2483         st->print("...");
2484         break;
2485       }
2486     }
2487   }
2488 }
2489 
2490 void Node::set_debug_orig(Node* orig) {
2491   _debug_orig = orig;
2492   if (BreakAtNode == 0)  return;
2493   if (not_a_node(orig))  orig = nullptr;
2494   int trip = 10;
2495   while (orig != nullptr) {
2496     if (orig->debug_idx() == BreakAtNode || (uintx)orig->_idx == BreakAtNode) {
2497       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT " orig._idx=%d orig._debug_idx=" UINT64_FORMAT,
2498                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
2499       BREAKPOINT;
2500     }
2501     orig = orig->debug_orig();
2502     if (not_a_node(orig))  orig = nullptr;
2503     if (trip-- <= 0)  break;
2504   }
2505 }
2506 #endif //ASSERT
2507 
2508 //------------------------------dump------------------------------------------
2509 // Dump a Node
2510 void Node::dump(const char* suffix, bool mark, outputStream* st, DumpConfig* dc) const {
2511   Compile* C = Compile::current();
2512   bool is_new = C->node_arena()->contains(this);
2513   C->_in_dump_cnt++;
2514 
2515   // idx mark name ===
2516   dump_idx(true, st, dc);
2517   st->print(mark ? " >" : "  ");
2518   dump_name(st, dc);
2519   st->print("  === ");
2520 
2521   // Dump the required and precedence inputs
2522   dump_req(st, dc);
2523   dump_prec(st, dc);
2524   // Dump the outputs
2525   dump_out(st, dc);
2526 
2527   if (is_disconnected(this)) {
2528 #ifdef ASSERT
2529     st->print("  [" UINT64_FORMAT "]", debug_idx());
2530     dump_orig(st);
2531 #endif
2532     st->cr();
2533     C->_in_dump_cnt--;
2534     return;                     // don't process dead nodes
2535   }
2536 
2537   if (C->clone_map().value(_idx) != 0) {
2538     C->clone_map().dump(_idx, st);
2539   }
2540   // Dump node-specific info
2541   dump_spec(st);
2542 #ifdef ASSERT
2543   // Dump the non-reset _debug_idx
2544   if (Verbose && WizardMode) {
2545     st->print("  [" UINT64_FORMAT "]", debug_idx());
2546   }
2547 #endif
2548 
2549   const Type *t = bottom_type();
2550 
2551   if (t != nullptr && (t->isa_instptr() || t->isa_instklassptr())) {
2552     const TypeInstPtr  *toop = t->isa_instptr();
2553     const TypeInstKlassPtr *tkls = t->isa_instklassptr();
2554     if (toop) {
2555       st->print("  Oop:");
2556     } else if (tkls) {
2557       st->print("  Klass:");
2558     }
2559     t->dump_on(st);
2560   } else if (t == Type::MEMORY) {
2561     st->print("  Memory:");
2562     MemNode::dump_adr_type(this, adr_type(), st);
2563   } else if (Verbose || WizardMode) {
2564     st->print("  Type:");
2565     if (t) {
2566       t->dump_on(st);
2567     } else {
2568       st->print("no type");
2569     }
2570   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
2571     // Dump MachSpillcopy vector type.
2572     t->dump_on(st);
2573   }
2574   if (is_new) {
2575     DEBUG_ONLY(dump_orig(st));
2576     Node_Notes* nn = C->node_notes_at(_idx);
2577     if (nn != nullptr && !nn->is_clear()) {
2578       if (nn->jvms() != nullptr) {
2579         st->print(" !jvms:");
2580         nn->jvms()->dump_spec(st);
2581       }
2582     }
2583   }
2584   if (suffix) st->print("%s", suffix);
2585   C->_in_dump_cnt--;
2586 }
2587 
2588 // call from debugger: dump node to tty with newline
2589 void Node::dump() const {
2590   dump("\n");
2591 }
2592 
2593 //------------------------------dump_req--------------------------------------
2594 void Node::dump_req(outputStream* st, DumpConfig* dc) const {
2595   // Dump the required input edges
2596   for (uint i = 0; i < req(); i++) {    // For all required inputs
2597     Node* d = in(i);
2598     if (d == nullptr) {
2599       st->print("_ ");
2600     } else if (not_a_node(d)) {
2601       st->print("not_a_node ");  // uninitialized, sentinel, garbage, etc.
2602     } else {
2603       d->dump_idx(false, st, dc);
2604       st->print(" ");
2605     }
2606   }
2607 }
2608 
2609 
2610 //------------------------------dump_prec-------------------------------------
2611 void Node::dump_prec(outputStream* st, DumpConfig* dc) const {
2612   // Dump the precedence edges
2613   int any_prec = 0;
2614   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
2615     Node* p = in(i);
2616     if (p != nullptr) {
2617       if (!any_prec++) st->print(" |");
2618       if (not_a_node(p)) { st->print("not_a_node "); continue; }
2619       p->dump_idx(false, st, dc);
2620       st->print(" ");
2621     }
2622   }
2623 }
2624 
2625 //------------------------------dump_out--------------------------------------
2626 void Node::dump_out(outputStream* st, DumpConfig* dc) const {
2627   // Delimit the output edges
2628   st->print(" [[ ");
2629   // Dump the output edges
2630   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
2631     Node* u = _out[i];
2632     if (u == nullptr) {
2633       st->print("_ ");
2634     } else if (not_a_node(u)) {
2635       st->print("not_a_node ");
2636     } else {
2637       u->dump_idx(false, st, dc);
2638       st->print(" ");
2639     }
2640   }
2641   st->print("]] ");
2642 }
2643 
2644 //------------------------------dump-------------------------------------------
2645 // call from debugger: dump Node's inputs (or outputs if d negative)
2646 void Node::dump(int d) const {
2647   dump_bfs(abs(d), nullptr, (d > 0) ? "+$" : "-$");
2648 }
2649 
2650 //------------------------------dump_ctrl--------------------------------------
2651 // call from debugger: dump Node's control inputs (or outputs if d negative)
2652 void Node::dump_ctrl(int d) const {
2653   dump_bfs(abs(d), nullptr, (d > 0) ? "+$c" : "-$c");
2654 }
2655 
2656 //-----------------------------dump_compact------------------------------------
2657 void Node::dump_comp() const {
2658   this->dump_comp("\n");
2659 }
2660 
2661 //-----------------------------dump_compact------------------------------------
2662 // Dump a Node in compact representation, i.e., just print its name and index.
2663 // Nodes can specify additional specifics to print in compact representation by
2664 // implementing dump_compact_spec.
2665 void Node::dump_comp(const char* suffix, outputStream *st) const {
2666   Compile* C = Compile::current();
2667   C->_in_dump_cnt++;
2668   st->print("%s(%d)", Name(), _idx);
2669   this->dump_compact_spec(st);
2670   if (suffix) {
2671     st->print("%s", suffix);
2672   }
2673   C->_in_dump_cnt--;
2674 }
2675 
2676 // VERIFICATION CODE
2677 // Verify all nodes if verify_depth is negative
2678 void Node::verify(int verify_depth, VectorSet& visited, Node_List& worklist) {
2679   assert(verify_depth != 0, "depth should not be 0");
2680   Compile* C = Compile::current();
2681   uint last_index_on_current_depth = worklist.size() - 1;
2682   verify_depth--; // Visiting the first node on depth 1
2683   // Only add nodes to worklist if verify_depth is negative (visit all nodes) or greater than 0
2684   bool add_to_worklist = verify_depth != 0;
2685 
2686   for (uint list_index = 0; list_index < worklist.size(); list_index++) {
2687     Node* n = worklist[list_index];
2688 
2689     if (n->is_Con() && n->bottom_type() == Type::TOP) {
2690       if (C->cached_top_node() == nullptr) {
2691         C->set_cached_top_node((Node*)n);
2692       }
2693       assert(C->cached_top_node() == n, "TOP node must be unique");
2694     }
2695 
2696     uint in_len = n->len();
2697     for (uint i = 0; i < in_len; i++) {
2698       Node* x = n->_in[i];
2699       if (!x || x->is_top()) {
2700         continue;
2701       }
2702 
2703       // Verify my input has a def-use edge to me
2704       // Count use-def edges from n to x
2705       int cnt = 1;
2706       for (uint j = 0; j < i; j++) {
2707         if (n->_in[j] == x) {
2708           cnt++;
2709           break;
2710         }
2711       }
2712       if (cnt == 2) {
2713         // x is already checked as n's previous input, skip its duplicated def-use count checking
2714         continue;
2715       }
2716       for (uint j = i + 1; j < in_len; j++) {
2717         if (n->_in[j] == x) {
2718           cnt++;
2719         }
2720       }
2721 
2722       // Count def-use edges from x to n
2723       uint max = x->_outcnt;
2724       for (uint k = 0; k < max; k++) {
2725         if (x->_out[k] == n) {
2726           cnt--;
2727         }
2728       }
2729       assert(cnt == 0, "mismatched def-use edge counts");
2730 
2731       if (add_to_worklist && !visited.test_set(x->_idx)) {
2732         worklist.push(x);
2733       }
2734     }
2735 
2736     if (verify_depth > 0 && list_index == last_index_on_current_depth) {
2737       // All nodes on this depth were processed and its inputs are on the worklist. Decrement verify_depth and
2738       // store the current last list index which is the last node in the list with the new depth. All nodes
2739       // added afterwards will have a new depth again. Stop adding new nodes if depth limit is reached (=0).
2740       verify_depth--;
2741       if (verify_depth == 0) {
2742         add_to_worklist = false;
2743       }
2744       last_index_on_current_depth = worklist.size() - 1;
2745     }
2746   }
2747 }
2748 #endif // not PRODUCT
2749 
2750 //------------------------------Registers--------------------------------------
2751 // Do we Match on this edge index or not?  Generally false for Control
2752 // and true for everything else.  Weird for calls & returns.
2753 uint Node::match_edge(uint idx) const {
2754   return idx;                   // True for other than index 0 (control)
2755 }
2756 
2757 // Register classes are defined for specific machines
2758 const RegMask &Node::out_RegMask() const {
2759   ShouldNotCallThis();
2760   return RegMask::Empty;
2761 }
2762 
2763 const RegMask &Node::in_RegMask(uint) const {
2764   ShouldNotCallThis();
2765   return RegMask::Empty;
2766 }
2767 
2768 void Node_Array::grow(uint i) {
2769   assert(_max > 0, "invariant");
2770   uint old = _max;
2771   _max = next_power_of_2(i);
2772   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2773   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2774 }
2775 
2776 void Node_Array::insert(uint i, Node* n) {
2777   if (_nodes[_max - 1]) {
2778     grow(_max);
2779   }
2780   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i + 1], ((_max - i - 1) * sizeof(Node*)));
2781   _nodes[i] = n;
2782 }
2783 
2784 void Node_Array::remove(uint i) {
2785   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i + 1], (HeapWord*)&_nodes[i], ((_max - i - 1) * sizeof(Node*)));
2786   _nodes[_max - 1] = nullptr;
2787 }
2788 
2789 void Node_Array::dump() const {
2790 #ifndef PRODUCT
2791   for (uint i = 0; i < _max; i++) {
2792     Node* nn = _nodes[i];
2793     if (nn != nullptr) {
2794       tty->print("%5d--> ",i); nn->dump();
2795     }
2796   }
2797 #endif
2798 }
2799 
2800 //--------------------------is_iteratively_computed------------------------------
2801 // Operation appears to be iteratively computed (such as an induction variable)
2802 // It is possible for this operation to return false for a loop-varying
2803 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2804 bool Node::is_iteratively_computed() {
2805   if (ideal_reg()) { // does operation have a result register?
2806     for (uint i = 1; i < req(); i++) {
2807       Node* n = in(i);
2808       if (n != nullptr && n->is_Phi()) {
2809         for (uint j = 1; j < n->req(); j++) {
2810           if (n->in(j) == this) {
2811             return true;
2812           }
2813         }
2814       }
2815     }
2816   }
2817   return false;
2818 }
2819 
2820 //--------------------------find_similar------------------------------
2821 // Return a node with opcode "opc" and same inputs as "this" if one can
2822 // be found; Otherwise return null;
2823 Node* Node::find_similar(int opc) {
2824   if (req() >= 2) {
2825     Node* def = in(1);
2826     if (def && def->outcnt() >= 2) {
2827       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2828         Node* use = def->fast_out(i);
2829         if (use != this &&
2830             use->Opcode() == opc &&
2831             use->req() == req()) {
2832           uint j;
2833           for (j = 0; j < use->req(); j++) {
2834             if (use->in(j) != in(j)) {
2835               break;
2836             }
2837           }
2838           if (j == use->req()) {
2839             return use;
2840           }
2841         }
2842       }
2843     }
2844   }
2845   return nullptr;
2846 }
2847 
2848 
2849 //--------------------------unique_ctrl_out_or_null-------------------------
2850 // Return the unique control out if only one. Null if none or more than one.
2851 Node* Node::unique_ctrl_out_or_null() const {
2852   Node* found = nullptr;
2853   for (uint i = 0; i < outcnt(); i++) {
2854     Node* use = raw_out(i);
2855     if (use->is_CFG() && use != this) {
2856       if (found != nullptr) {
2857         return nullptr;
2858       }
2859       found = use;
2860     }
2861   }
2862   return found;
2863 }
2864 
2865 //--------------------------unique_ctrl_out------------------------------
2866 // Return the unique control out. Asserts if none or more than one control out.
2867 Node* Node::unique_ctrl_out() const {
2868   Node* ctrl = unique_ctrl_out_or_null();
2869   assert(ctrl != nullptr, "control out is assumed to be unique");
2870   return ctrl;
2871 }
2872 
2873 void Node::ensure_control_or_add_prec(Node* c) {
2874   if (in(0) == nullptr) {
2875     set_req(0, c);
2876   } else if (in(0) != c) {
2877     add_prec(c);
2878   }
2879 }
2880 
2881 bool Node::is_dead_loop_safe() const {
2882   if (is_Phi()) {
2883     return true;
2884   }
2885   if (is_Proj() && in(0) == nullptr)  {
2886     return true;
2887   }
2888   if ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0) {
2889     if (!is_Proj()) {
2890       return true;
2891     }
2892     if (in(0)->is_Allocate()) {
2893       return false;
2894     }
2895     // MemNode::can_see_stored_value() peeks through the boxing call
2896     if (in(0)->is_CallStaticJava() && in(0)->as_CallStaticJava()->is_boxing_method()) {
2897       return false;
2898     }
2899     return true;
2900   }
2901   return false;
2902 }
2903 
2904 //=============================================================================
2905 //------------------------------yank-------------------------------------------
2906 // Find and remove
2907 void Node_List::yank( Node *n ) {
2908   uint i;
2909   for (i = 0; i < _cnt; i++) {
2910     if (_nodes[i] == n) {
2911       break;
2912     }
2913   }
2914 
2915   if (i < _cnt) {
2916     _nodes[i] = _nodes[--_cnt];
2917   }
2918 }
2919 
2920 //------------------------------dump-------------------------------------------
2921 void Node_List::dump() const {
2922 #ifndef PRODUCT
2923   for (uint i = 0; i < _cnt; i++) {
2924     if (_nodes[i]) {
2925       tty->print("%5d--> ", i);
2926       _nodes[i]->dump();
2927     }
2928   }
2929 #endif
2930 }
2931 
2932 void Node_List::dump_simple() const {
2933 #ifndef PRODUCT
2934   for (uint i = 0; i < _cnt; i++) {
2935     if( _nodes[i] ) {
2936       tty->print(" %d", _nodes[i]->_idx);
2937     } else {
2938       tty->print(" null");
2939     }
2940   }
2941 #endif
2942 }
2943 
2944 //=============================================================================
2945 //------------------------------remove-----------------------------------------
2946 void Unique_Node_List::remove(Node* n) {
2947   if (_in_worklist.test(n->_idx)) {
2948     for (uint i = 0; i < size(); i++) {
2949       if (_nodes[i] == n) {
2950         map(i, Node_List::pop());
2951         _in_worklist.remove(n->_idx);
2952         return;
2953       }
2954     }
2955     ShouldNotReachHere();
2956   }
2957 }
2958 
2959 //-----------------------remove_useless_nodes----------------------------------
2960 // Remove useless nodes from worklist
2961 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2962   for (uint i = 0; i < size(); ++i) {
2963     Node *n = at(i);
2964     assert( n != nullptr, "Did not expect null entries in worklist");
2965     if (!useful.test(n->_idx)) {
2966       _in_worklist.remove(n->_idx);
2967       map(i, Node_List::pop());
2968       --i;  // Visit popped node
2969       // If it was last entry, loop terminates since size() was also reduced
2970     }
2971   }
2972 }
2973 
2974 //=============================================================================
2975 void Node_Stack::grow() {
2976   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2977   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2978   size_t max = old_max << 1;             // max * 2
2979   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2980   _inode_max = _inodes + max;
2981   _inode_top = _inodes + old_top;        // restore _top
2982 }
2983 
2984 // Node_Stack is used to map nodes.
2985 Node* Node_Stack::find(uint idx) const {
2986   uint sz = size();
2987   for (uint i = 0; i < sz; i++) {
2988     if (idx == index_at(i)) {
2989       return node_at(i);
2990     }
2991   }
2992   return nullptr;
2993 }
2994 
2995 //=============================================================================
2996 uint TypeNode::size_of() const { return sizeof(*this); }
2997 #ifndef PRODUCT
2998 void TypeNode::dump_spec(outputStream *st) const {
2999   if (!Verbose && !WizardMode) {
3000     // standard dump does this in Verbose and WizardMode
3001     st->print(" #"); _type->dump_on(st);
3002   }
3003 }
3004 
3005 void TypeNode::dump_compact_spec(outputStream *st) const {
3006   st->print("#");
3007   _type->dump_on(st);
3008 }
3009 #endif
3010 uint TypeNode::hash() const {
3011   return Node::hash() + _type->hash();
3012 }
3013 bool TypeNode::cmp(const Node& n) const {
3014   return !Type::cmp(_type, ((TypeNode&)n)._type);
3015 }
3016 const Type* TypeNode::bottom_type() const { return _type; }
3017 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
3018 
3019 //------------------------------ideal_reg--------------------------------------
3020 uint TypeNode::ideal_reg() const {
3021   return _type->ideal_reg();
3022 }
--- EOF ---